diff --git a/dev-libs/glib/files/glib-2.74.1-normal-form-handling-gvariant-patch-fixes.patch b/dev-libs/glib/files/glib-2.74.1-normal-form-handling-gvariant-patch-fixes.patch
new file mode 100644
index 0000000..612d2ab
--- /dev/null
+++ b/dev-libs/glib/files/glib-2.74.1-normal-form-handling-gvariant-patch-fixes.patch
@@ -0,0 +1,200 @@
+From bf008669f26f70426ca30ee8cdcbd48e41a74718 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Thu, 15 Dec 2022 13:00:39 +0000
+Subject: [PATCH 1/2] =?UTF-8?q?gvariant:=20Check=20offset=20table=20doesn?=
+ =?UTF-8?q?=E2=80=99t=20fall=20outside=20variant=20bounds?=
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+When dereferencing the first entry in the offset table for a tuple,
+check that it doesn’t fall outside the bounds of the variant first.
+
+This prevents an out-of-bounds read from some non-normal tuples.
+
+This bug was introduced in commit 73d0aa81c2575a5c9ae77d.
+
+Includes a unit test, although the test will likely only catch the
+original bug if run with asan enabled.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Fixes: #2840
+oss-fuzz#54302
+---
+ glib/gvariant-serialiser.c | 12 ++++++--
+ glib/tests/gvariant.c      | 63 ++++++++++++++++++++++++++++++++++++++
+ 2 files changed, 72 insertions(+), 3 deletions(-)
+
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index e9b0eab2b4..af863cc526 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -984,7 +984,8 @@ gvs_tuple_get_member_bounds (GVariantSerialised  value,
+ 
+   member_info = g_variant_type_info_member_info (value.type_info, index_);
+ 
+-  if (member_info->i + 1)
++  if (member_info->i + 1 &&
++      offset_size * (member_info->i + 1) <= value.size)
+     member_start = gvs_read_unaligned_le (value.data + value.size -
+                                           offset_size * (member_info->i + 1),
+                                           offset_size);
+@@ -995,7 +996,8 @@ gvs_tuple_get_member_bounds (GVariantSerialised  value,
+   member_start &= member_info->b;
+   member_start |= member_info->c;
+ 
+-  if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_LAST)
++  if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_LAST &&
++      offset_size * (member_info->i + 1) <= value.size)
+     member_end = value.size - offset_size * (member_info->i + 1);
+ 
+   else if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_FIXED)
+@@ -1006,11 +1008,15 @@ gvs_tuple_get_member_bounds (GVariantSerialised  value,
+       member_end = member_start + fixed_size;
+     }
+ 
+-  else /* G_VARIANT_MEMBER_ENDING_OFFSET */
++  else if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_OFFSET &&
++           offset_size * (member_info->i + 2) <= value.size)
+     member_end = gvs_read_unaligned_le (value.data + value.size -
+                                         offset_size * (member_info->i + 2),
+                                         offset_size);
+ 
++  else  /* invalid */
++    member_end = G_MAXSIZE;
++
+   if (out_member_start != NULL)
+     *out_member_start = member_start;
+   if (out_member_end != NULL)
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index ba837af48d..e4a2518aa6 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -5562,6 +5562,67 @@ test_normal_checking_tuple_offsets4 (void)
+   g_variant_unref (variant);
+ }
+ 
++/* This is a regression test that dereferencing the first element in the offset
++ * table doesn’t dereference memory before the start of the GVariant. The first
++ * element in the offset table gives the offset of the final member in the
++ * tuple (the offset table is stored in reverse), and the position of this final
++ * member is needed to check that none of the tuple members overlap with the
++ * offset table
++ *
++ * See https://gitlab.gnome.org/GNOME/glib/-/issues/2840 */
++static void
++test_normal_checking_tuple_offsets5 (void)
++{
++  /* A tuple of type (sss) in normal form would have an offset table with two
++   * entries:
++   *  - The first entry (lowest index in the table) gives the offset of the
++   *    third `s` in the tuple, as the offset table is reversed compared to the
++   *    tuple members.
++   *  - The second entry (highest index in the table) gives the offset of the
++   *    second `s` in the tuple.
++   *  - The offset of the first `s` in the tuple is always 0.
++   *
++   * See §2.5.4 (Structures) of the GVariant specification for details, noting
++   * that the table is only layed out this way because all three members of the
++   * tuple have non-fixed sizes.
++   *
++   * It’s not clear whether the 0xaa data of this variant is part of the strings
++   * in the tuple, or part of the offset table. It doesn’t really matter. This
++   * is a regression test to check that the code to validate the offset table
++   * doesn’t unconditionally try to access the first entry in the offset table
++   * by subtracting the table size from the end of the GVariant data.
++   *
++   * In this non-normal case, that would result in an address off the start of
++   * the GVariant data, and an out-of-bounds read, because the GVariant is one
++   * byte long, but the offset table is calculated as two bytes long (with 1B
++   * sized entries) from the tuple’s type.
++   */
++  const GVariantType *data_type = G_VARIANT_TYPE ("(sss)");
++  const guint8 data[] = { 0xaa };
++  gsize size = sizeof (data);
++  GVariant *variant = NULL;
++  GVariant *normal_variant = NULL;
++  GVariant *expected = NULL;
++
++  g_test_bug ("https://gitlab.gnome.org/GNOME/glib/-/issues/2840");
++
++  variant = g_variant_new_from_data (data_type, data, size, FALSE, NULL, NULL);
++  g_assert_nonnull (variant);
++
++  g_assert_false (g_variant_is_normal_form (variant));
++
++  normal_variant = g_variant_get_normal_form (variant);
++  g_assert_nonnull (normal_variant);
++
++  expected = g_variant_new_parsed ("('', '', '')");
++  g_assert_cmpvariant (expected, variant);
++  g_assert_cmpvariant (expected, normal_variant);
++
++  g_variant_unref (expected);
++  g_variant_unref (normal_variant);
++  g_variant_unref (variant);
++}
++
+ /* Test that an otherwise-valid serialised GVariant is considered non-normal if
+  * its offset table entries are too wide.
+  *
+@@ -5813,6 +5874,8 @@ main (int argc, char **argv)
+                    test_normal_checking_tuple_offsets3);
+   g_test_add_func ("/gvariant/normal-checking/tuple-offsets4",
+                    test_normal_checking_tuple_offsets4);
++  g_test_add_func ("/gvariant/normal-checking/tuple-offsets5",
++                   test_normal_checking_tuple_offsets5);
+   g_test_add_func ("/gvariant/normal-checking/tuple-offsets/minimal-sized",
+                    test_normal_checking_tuple_offsets_minimal_sized);
+   g_test_add_func ("/gvariant/normal-checking/empty-object-path",
+-- 
+GitLab
+
+
+From 4d0bed8c4690f7a2692474ef6a570bd99ef45ef1 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Thu, 15 Dec 2022 16:49:28 +0000
+Subject: [PATCH 2/2] gvariant: Propagate trust when getting a child of a
+ serialised variant
+
+If a variant is trusted, that means all its children are trusted, so
+ensure that their checked offsets are set as such.
+
+This allows a lot of the offset table checks to be avoided when getting
+children from trusted serialised tuples, which speeds things up.
+
+No unit test is included because this is just a performance fix. If
+there are other slownesses, or regressions, in serialised `GVariant`
+performance, the fuzzing setup will catch them like it did this one.
+
+This change does reduce the time to run the oss-fuzz reproducer from 80s
+to about 0.7s on my machine.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Fixes: #2841
+oss-fuzz#54314
+---
+ glib/gvariant-core.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
+index 75d23f39af..57bbf88cc9 100644
+--- a/glib/gvariant-core.c
++++ b/glib/gvariant-core.c
+@@ -1198,8 +1198,8 @@ g_variant_get_child_value (GVariant *value,
+     child->contents.serialised.bytes =
+       g_bytes_ref (value->contents.serialised.bytes);
+     child->contents.serialised.data = s_child.data;
+-    child->contents.serialised.ordered_offsets_up_to = s_child.ordered_offsets_up_to;
+-    child->contents.serialised.checked_offsets_up_to = s_child.checked_offsets_up_to;
++    child->contents.serialised.ordered_offsets_up_to = (value->state & STATE_TRUSTED) ? G_MAXSIZE : s_child.ordered_offsets_up_to;
++    child->contents.serialised.checked_offsets_up_to = (value->state & STATE_TRUSTED) ? G_MAXSIZE : s_child.checked_offsets_up_to;
+ 
+     return child;
+   }
+-- 
+GitLab
+
+
diff --git a/dev-libs/glib/files/glib-2.74.1-normal-form-handling-gvariant.patch b/dev-libs/glib/files/glib-2.74.1-normal-form-handling-gvariant.patch
new file mode 100644
index 0000000..1d75331
--- /dev/null
+++ b/dev-libs/glib/files/glib-2.74.1-normal-form-handling-gvariant.patch
@@ -0,0 +1,2975 @@
+From 590f7a6b76b5a3695aa562c9c3ab244433b6624b Mon Sep 17 00:00:00 2001
+From: William Manley <will@stb-tester.com>
+Date: Tue, 23 Jun 2020 22:59:58 +0100
+Subject: [PATCH 01/18] gvariant-core: Consolidate construction of
+ `GVariantSerialised`
+
+So I only need to change it in one place.
+
+This introduces no functional changes.
+
+Helps: #2121
+---
+ glib/gvariant-core.c | 49 ++++++++++++++++++++++----------------------
+ 1 file changed, 25 insertions(+), 24 deletions(-)
+
+diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
+index ad0bab5b62..70c712ddc0 100644
+--- a/glib/gvariant-core.c
++++ b/glib/gvariant-core.c
+@@ -351,6 +351,27 @@ g_variant_ensure_size (GVariant *value)
+     }
+ }
+ 
++/* < private >
++ * g_variant_to_serialised:
++ * @value: a #GVariant
++ *
++ * Gets a GVariantSerialised for a GVariant in state STATE_SERIALISED.
++ */
++inline static GVariantSerialised
++g_variant_to_serialised (GVariant *value)
++{
++  g_assert (value->state & STATE_SERIALISED);
++  {
++    GVariantSerialised serialised = {
++      value->type_info,
++      (gpointer) value->contents.serialised.data,
++      value->size,
++      value->depth,
++    };
++    return serialised;
++  }
++}
++
+ /* < private >
+  * g_variant_serialise:
+  * @value: a #GVariant
+@@ -1009,16 +1030,8 @@ g_variant_n_children (GVariant *value)
+   g_variant_lock (value);
+ 
+   if (value->state & STATE_SERIALISED)
+-    {
+-      GVariantSerialised serialised = {
+-        value->type_info,
+-        (gpointer) value->contents.serialised.data,
+-        value->size,
+-        value->depth,
+-      };
+-
+-      n_children = g_variant_serialised_n_children (serialised);
+-    }
++    n_children = g_variant_serialised_n_children (
++        g_variant_to_serialised (value));
+   else
+     n_children = value->contents.tree.n_children;
+ 
+@@ -1085,12 +1098,7 @@ g_variant_get_child_value (GVariant *value,
+     }
+ 
+   {
+-    GVariantSerialised serialised = {
+-      value->type_info,
+-      (gpointer) value->contents.serialised.data,
+-      value->size,
+-      value->depth,
+-    };
++    GVariantSerialised serialised = g_variant_to_serialised (value);
+     GVariantSerialised s_child;
+     GVariant *child;
+ 
+@@ -1203,14 +1211,7 @@ g_variant_is_normal_form (GVariant *value)
+ 
+   if (value->state & STATE_SERIALISED)
+     {
+-      GVariantSerialised serialised = {
+-        value->type_info,
+-        (gpointer) value->contents.serialised.data,
+-        value->size,
+-        value->depth
+-      };
+-
+-      if (g_variant_serialised_is_normal (serialised))
++      if (g_variant_serialised_is_normal (g_variant_to_serialised (value)))
+         value->state |= STATE_TRUSTED;
+     }
+   else
+-- 
+GitLab
+
+
+From f8f5d8eefa06008aa8fe684069193dc3b1ae1b58 Mon Sep 17 00:00:00 2001
+From: William Manley <will@stb-tester.com>
+Date: Thu, 25 Jun 2020 17:08:21 +0100
+Subject: [PATCH 02/18] gvariant-serialiser: Factor out functions for dealing
+ with framing offsets
+
+This introduces no functional changes.
+
+Helps: #2121
+---
+ glib/gvariant-serialiser.c | 108 +++++++++++++++++++------------------
+ 1 file changed, 57 insertions(+), 51 deletions(-)
+
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index 3af68b79b2..09492e4526 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -635,30 +635,62 @@ gvs_calculate_total_size (gsize body_size,
+   return body_size + 8 * offsets;
+ }
+ 
++struct Offsets
++{
++  gsize     data_size;
++
++  guchar   *array;
++  gsize     length;
++  guint     offset_size;
++
++  gboolean  is_normal;
++};
++
+ static gsize
+-gvs_variable_sized_array_n_children (GVariantSerialised value)
++gvs_offsets_get_offset_n (struct Offsets *offsets,
++                          gsize           n)
++{
++  return gvs_read_unaligned_le (
++      offsets->array + (offsets->offset_size * n), offsets->offset_size);
++}
++
++static struct Offsets
++gvs_variable_sized_array_get_frame_offsets (GVariantSerialised value)
+ {
++  struct Offsets out = { 0, };
+   gsize offsets_array_size;
+-  gsize offset_size;
+   gsize last_end;
+ 
+   if (value.size == 0)
+-    return 0;
+-
+-  offset_size = gvs_get_offset_size (value.size);
++    {
++      out.is_normal = TRUE;
++      return out;
++    }
+ 
+-  last_end = gvs_read_unaligned_le (value.data + value.size -
+-                                    offset_size, offset_size);
++  out.offset_size = gvs_get_offset_size (value.size);
++  last_end = gvs_read_unaligned_le (value.data + value.size - out.offset_size,
++                                    out.offset_size);
+ 
+   if (last_end > value.size)
+-    return 0;
++    return out;  /* offsets not normal */
+ 
+   offsets_array_size = value.size - last_end;
+ 
+-  if (offsets_array_size % offset_size)
+-    return 0;
++  if (offsets_array_size % out.offset_size)
++    return out;  /* offsets not normal */
++
++  out.data_size = last_end;
++  out.array = value.data + last_end;
++  out.length = offsets_array_size / out.offset_size;
++  out.is_normal = TRUE;
+ 
+-  return offsets_array_size / offset_size;
++  return out;
++}
++
++static gsize
++gvs_variable_sized_array_n_children (GVariantSerialised value)
++{
++  return gvs_variable_sized_array_get_frame_offsets (value).length;
+ }
+ 
+ static GVariantSerialised
+@@ -666,8 +698,9 @@ gvs_variable_sized_array_get_child (GVariantSerialised value,
+                                     gsize              index_)
+ {
+   GVariantSerialised child = { 0, };
+-  gsize offset_size;
+-  gsize last_end;
++
++  struct Offsets offsets = gvs_variable_sized_array_get_frame_offsets (value);
++
+   gsize start;
+   gsize end;
+ 
+@@ -675,18 +708,11 @@ gvs_variable_sized_array_get_child (GVariantSerialised value,
+   g_variant_type_info_ref (child.type_info);
+   child.depth = value.depth + 1;
+ 
+-  offset_size = gvs_get_offset_size (value.size);
+-
+-  last_end = gvs_read_unaligned_le (value.data + value.size -
+-                                    offset_size, offset_size);
+-
+   if (index_ > 0)
+     {
+       guint alignment;
+ 
+-      start = gvs_read_unaligned_le (value.data + last_end +
+-                                     (offset_size * (index_ - 1)),
+-                                     offset_size);
++      start = gvs_offsets_get_offset_n (&offsets, index_ - 1);
+ 
+       g_variant_type_info_query (child.type_info, &alignment, NULL);
+       start += (-start) & alignment;
+@@ -694,11 +720,9 @@ gvs_variable_sized_array_get_child (GVariantSerialised value,
+   else
+     start = 0;
+ 
+-  end = gvs_read_unaligned_le (value.data + last_end +
+-                               (offset_size * index_),
+-                               offset_size);
++  end = gvs_offsets_get_offset_n (&offsets, index_);
+ 
+-  if (start < end && end <= value.size && end <= last_end)
++  if (start < end && end <= value.size && end <= offsets.data_size)
+     {
+       child.data = value.data + start;
+       child.size = end - start;
+@@ -770,34 +794,16 @@ static gboolean
+ gvs_variable_sized_array_is_normal (GVariantSerialised value)
+ {
+   GVariantSerialised child = { 0, };
+-  gsize offsets_array_size;
+-  guchar *offsets_array;
+-  guint offset_size;
+   guint alignment;
+-  gsize last_end;
+-  gsize length;
+   gsize offset;
+   gsize i;
+ 
+-  if (value.size == 0)
+-    return TRUE;
+-
+-  offset_size = gvs_get_offset_size (value.size);
+-  last_end = gvs_read_unaligned_le (value.data + value.size -
+-                                    offset_size, offset_size);
++  struct Offsets offsets = gvs_variable_sized_array_get_frame_offsets (value);
+ 
+-  if (last_end > value.size)
++  if (!offsets.is_normal)
+     return FALSE;
+ 
+-  offsets_array_size = value.size - last_end;
+-
+-  if (offsets_array_size % offset_size)
+-    return FALSE;
+-
+-  offsets_array = value.data + value.size - offsets_array_size;
+-  length = offsets_array_size / offset_size;
+-
+-  if (length == 0)
++  if (value.size != 0 && offsets.length == 0)
+     return FALSE;
+ 
+   child.type_info = g_variant_type_info_element (value.type_info);
+@@ -805,14 +811,14 @@ gvs_variable_sized_array_is_normal (GVariantSerialised value)
+   child.depth = value.depth + 1;
+   offset = 0;
+ 
+-  for (i = 0; i < length; i++)
++  for (i = 0; i < offsets.length; i++)
+     {
+       gsize this_end;
+ 
+-      this_end = gvs_read_unaligned_le (offsets_array + offset_size * i,
+-                                        offset_size);
++      this_end = gvs_read_unaligned_le (offsets.array + offsets.offset_size * i,
++                                        offsets.offset_size);
+ 
+-      if (this_end < offset || this_end > last_end)
++      if (this_end < offset || this_end > offsets.data_size)
+         return FALSE;
+ 
+       while (offset & alignment)
+@@ -834,7 +840,7 @@ gvs_variable_sized_array_is_normal (GVariantSerialised value)
+       offset = this_end;
+     }
+ 
+-  g_assert (offset == last_end);
++  g_assert (offset == offsets.data_size);
+ 
+   return TRUE;
+ }
+-- 
+GitLab
+
+
+From 5c27f22aff636766fbc5e49927fd28213629e840 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Tue, 25 Oct 2022 18:05:52 +0100
+Subject: [PATCH 03/18] gvariant: Zero-initialise various GVariantSerialised
+ objects
+
+The following few commits will add a couple of new fields to
+`GVariantSerialised`, and they should be zero-filled by default.
+
+Try and pre-empt that a bit by zero-filling `GVariantSerialised` by
+default in a few places.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2121
+---
+ glib/gvariant.c       |  2 +-
+ glib/tests/gvariant.c | 12 ++++++------
+ 2 files changed, 7 insertions(+), 7 deletions(-)
+
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index 93eb6cb6bc..6912eebe05 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -6001,7 +6001,7 @@ g_variant_byteswap (GVariant *value)
+   if (alignment)
+     /* (potentially) contains multi-byte numeric data */
+     {
+-      GVariantSerialised serialised;
++      GVariantSerialised serialised = { 0, };
+       GVariant *trusted;
+       GBytes *bytes;
+ 
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index 29110e4e24..1a57dc6ef7 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -1440,7 +1440,7 @@ test_maybe (void)
+ 
+     for (flavour = 0; flavour < 8; flavour += alignment)
+       {
+-        GVariantSerialised serialised;
++        GVariantSerialised serialised = { 0, };
+         GVariantSerialised child;
+ 
+         serialised.type_info = type_info;
+@@ -1564,7 +1564,7 @@ test_array (void)
+ 
+     for (flavour = 0; flavour < 8; flavour += alignment)
+       {
+-        GVariantSerialised serialised;
++        GVariantSerialised serialised = { 0, };
+ 
+         serialised.type_info = array_info;
+         serialised.data = flavoured_malloc (needed_size, flavour);
+@@ -1728,7 +1728,7 @@ test_tuple (void)
+ 
+     for (flavour = 0; flavour < 8; flavour += alignment)
+       {
+-        GVariantSerialised serialised;
++        GVariantSerialised serialised = { 0, };
+ 
+         serialised.type_info = type_info;
+         serialised.data = flavoured_malloc (needed_size, flavour);
+@@ -1823,7 +1823,7 @@ test_variant (void)
+ 
+     for (flavour = 0; flavour < 8; flavour += alignment)
+       {
+-        GVariantSerialised serialised;
++        GVariantSerialised serialised = { 0, };
+         GVariantSerialised child;
+ 
+         serialised.type_info = type_info;
+@@ -2270,7 +2270,7 @@ serialise_tree (TreeInstance       *tree,
+ static void
+ test_byteswap (void)
+ {
+-  GVariantSerialised one, two;
++  GVariantSerialised one = { 0, }, two = { 0, };
+   TreeInstance *tree;
+ 
+   tree = tree_instance_new (NULL, 3);
+@@ -2344,7 +2344,7 @@ test_serialiser_children (void)
+ static void
+ test_fuzz (gdouble *fuzziness)
+ {
+-  GVariantSerialised serialised;
++  GVariantSerialised serialised = { 0, };
+   TreeInstance *tree;
+ 
+   /* make an instance */
+-- 
+GitLab
+
+
+From c8067857f7c8fb369ecb30bb534b018b2e2b8f87 Mon Sep 17 00:00:00 2001
+From: William Manley <will@stb-tester.com>
+Date: Mon, 29 Jun 2020 16:59:44 +0100
+Subject: [PATCH 04/18] =?UTF-8?q?gvariant:=20Don=E2=80=99t=20allow=20child?=
+ =?UTF-8?q?=20elements=20to=20overlap=20with=20each=20other?=
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+If different elements of a variable sized array can overlap with each
+other then we can cause a `GVariant` to normalise to a much larger type.
+
+This commit changes the behaviour of `GVariant` with non-normal form data. If
+an invalid frame offset is found all subsequent elements are given their
+default value.
+
+When retrieving an element at index `n` we scan the frame offsets up to index
+`n` and if they are not in order we return an element with the default value
+for that type.  This guarantees that elements don't overlap with each
+other.  We remember the offset we've scanned up to so we don't need to
+repeat this work on subsequent accesses.  We skip these checks for trusted
+data.
+
+Unfortunately this makes random access of untrusted data O(n) — at least
+on first access.  It doesn't affect the algorithmic complexity of accessing
+elements in order, such as when using the `GVariantIter` interface.  Also:
+the cost of validation will be amortised as the `GVariant` instance is
+continued to be used.
+
+I've implemented this with 4 different functions, 1 for each element size,
+rather than looping calling `gvs_read_unaligned_le` in the hope that the
+compiler will find it easy to optimise and should produce fairly tight
+code.
+
+Fixes: #2121
+---
+ glib/gvariant-core.c       | 35 ++++++++++++++++
+ glib/gvariant-serialiser.c | 86 ++++++++++++++++++++++++++++++++++++--
+ glib/gvariant-serialiser.h |  9 ++++
+ glib/tests/gvariant.c      | 45 ++++++++++++++++++++
+ 4 files changed, 172 insertions(+), 3 deletions(-)
+
+diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
+index 70c712ddc0..a75e7db9ea 100644
+--- a/glib/gvariant-core.c
++++ b/glib/gvariant-core.c
+@@ -67,6 +67,7 @@ struct _GVariant
+     {
+       GBytes *bytes;
+       gconstpointer data;
++      gsize ordered_offsets_up_to;
+     } serialised;
+ 
+     struct
+@@ -164,6 +165,24 @@ struct _GVariant
+  *                if .data pointed to the appropriate number of nul
+  *                bytes.
+  *
++ *     .ordered_offsets_up_to: If ordered_offsets_up_to == n this means that all
++ *                             the frame offsets up to and including the frame
++ *                             offset determining the end of element n are in
++ *                             order. This guarantees that the bytes of element
++ *                             n don't overlap with any previous element.
++ *
++ *                             For trusted data this is set to G_MAXSIZE and we
++ *                             don't check that the frame offsets are in order.
++ *
++ *                             Note: This doesn't imply the offsets are good in
++ *                             any way apart from their ordering.  In particular
++ *                             offsets may be out of bounds for this value or
++ *                             may imply that the data overlaps the frame
++ *                             offsets themselves.
++ *
++ *                             This field is only relevant for arrays of non
++ *                             fixed width types.
++ *
+  *   .tree: Only valid when the instance is in tree form.
+  *
+  *          Note that accesses from other threads could result in
+@@ -367,6 +386,7 @@ g_variant_to_serialised (GVariant *value)
+       (gpointer) value->contents.serialised.data,
+       value->size,
+       value->depth,
++      value->contents.serialised.ordered_offsets_up_to,
+     };
+     return serialised;
+   }
+@@ -398,6 +418,7 @@ g_variant_serialise (GVariant *value,
+   serialised.size = value->size;
+   serialised.data = data;
+   serialised.depth = value->depth;
++  serialised.ordered_offsets_up_to = 0;
+ 
+   children = (gpointer *) value->contents.tree.children;
+   n_children = value->contents.tree.n_children;
+@@ -441,6 +462,15 @@ g_variant_fill_gvs (GVariantSerialised *serialised,
+   g_assert (serialised->size == value->size);
+   serialised->depth = value->depth;
+ 
++  if (value->state & STATE_SERIALISED)
++    {
++      serialised->ordered_offsets_up_to = value->contents.serialised.ordered_offsets_up_to;
++    }
++  else
++    {
++      serialised->ordered_offsets_up_to = 0;
++    }
++
+   if (serialised->data)
+     /* g_variant_store() is a public API, so it
+      * it will reacquire the lock if it needs to.
+@@ -483,6 +513,7 @@ g_variant_ensure_serialised (GVariant *value)
+       bytes = g_bytes_new_take (data, value->size);
+       value->contents.serialised.data = g_bytes_get_data (bytes, NULL);
+       value->contents.serialised.bytes = bytes;
++      value->contents.serialised.ordered_offsets_up_to = G_MAXSIZE;
+       value->state |= STATE_SERIALISED;
+     }
+ }
+@@ -563,6 +594,7 @@ g_variant_new_from_bytes (const GVariantType *type,
+   serialised.type_info = value->type_info;
+   serialised.data = (guchar *) g_bytes_get_data (bytes, &serialised.size);
+   serialised.depth = 0;
++  serialised.ordered_offsets_up_to = trusted ? G_MAXSIZE : 0;
+ 
+   if (!g_variant_serialised_check (serialised))
+     {
+@@ -613,6 +645,8 @@ g_variant_new_from_bytes (const GVariantType *type,
+       value->contents.serialised.data = g_bytes_get_data (bytes, &value->size);
+     }
+ 
++  value->contents.serialised.ordered_offsets_up_to = trusted ? G_MAXSIZE : 0;
++
+   g_clear_pointer (&owned_bytes, g_bytes_unref);
+ 
+   return value;
+@@ -1132,6 +1166,7 @@ g_variant_get_child_value (GVariant *value,
+     child->contents.serialised.bytes =
+       g_bytes_ref (value->contents.serialised.bytes);
+     child->contents.serialised.data = s_child.data;
++    child->contents.serialised.ordered_offsets_up_to = s_child.ordered_offsets_up_to;
+ 
+     return child;
+   }
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index 09492e4526..1aa2b8fa9b 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -1,6 +1,7 @@
+ /*
+  * Copyright © 2007, 2008 Ryan Lortie
+  * Copyright © 2010 Codethink Limited
++ * Copyright © 2020 William Manley
+  *
+  * SPDX-License-Identifier: LGPL-2.1-or-later
+  *
+@@ -266,6 +267,7 @@ gvs_fixed_sized_maybe_get_child (GVariantSerialised value,
+   value.type_info = g_variant_type_info_element (value.type_info);
+   g_variant_type_info_ref (value.type_info);
+   value.depth++;
++  value.ordered_offsets_up_to = 0;
+ 
+   return value;
+ }
+@@ -297,7 +299,7 @@ gvs_fixed_sized_maybe_serialise (GVariantSerialised        value,
+ {
+   if (n_children)
+     {
+-      GVariantSerialised child = { NULL, value.data, value.size, value.depth + 1 };
++      GVariantSerialised child = { NULL, value.data, value.size, value.depth + 1, 0 };
+ 
+       gvs_filler (&child, children[0]);
+     }
+@@ -319,6 +321,7 @@ gvs_fixed_sized_maybe_is_normal (GVariantSerialised value)
+       /* proper element size: "Just".  recurse to the child. */
+       value.type_info = g_variant_type_info_element (value.type_info);
+       value.depth++;
++      value.ordered_offsets_up_to = 0;
+ 
+       return g_variant_serialised_is_normal (value);
+     }
+@@ -360,6 +363,7 @@ gvs_variable_sized_maybe_get_child (GVariantSerialised value,
+     value.data = NULL;
+ 
+   value.depth++;
++  value.ordered_offsets_up_to = 0;
+ 
+   return value;
+ }
+@@ -390,7 +394,7 @@ gvs_variable_sized_maybe_serialise (GVariantSerialised        value,
+ {
+   if (n_children)
+     {
+-      GVariantSerialised child = { NULL, value.data, value.size - 1, value.depth + 1 };
++      GVariantSerialised child = { NULL, value.data, value.size - 1, value.depth + 1, 0 };
+ 
+       /* write the data for the child.  */
+       gvs_filler (&child, children[0]);
+@@ -410,6 +414,7 @@ gvs_variable_sized_maybe_is_normal (GVariantSerialised value)
+   value.type_info = g_variant_type_info_element (value.type_info);
+   value.size--;
+   value.depth++;
++  value.ordered_offsets_up_to = 0;
+ 
+   return g_variant_serialised_is_normal (value);
+ }
+@@ -693,6 +698,32 @@ gvs_variable_sized_array_n_children (GVariantSerialised value)
+   return gvs_variable_sized_array_get_frame_offsets (value).length;
+ }
+ 
++/* Find the index of the first out-of-order element in @data, assuming that
++ * @data is an array of elements of given @type, starting at index @start and
++ * containing a further @len-@start elements. */
++#define DEFINE_FIND_UNORDERED(type) \
++  static gsize \
++  find_unordered_##type (const guint8 *data, gsize start, gsize len) \
++  { \
++    gsize off; \
++    type current, previous; \
++    \
++    memcpy (&previous, data + start * sizeof (current), sizeof (current)); \
++    for (off = (start + 1) * sizeof (current); off < len * sizeof (current); off += sizeof (current)) \
++      { \
++        memcpy (&current, data + off, sizeof (current)); \
++        if (current < previous) \
++          break; \
++        previous = current; \
++      } \
++    return off / sizeof (current) - 1; \
++  }
++
++DEFINE_FIND_UNORDERED (guint8);
++DEFINE_FIND_UNORDERED (guint16);
++DEFINE_FIND_UNORDERED (guint32);
++DEFINE_FIND_UNORDERED (guint64);
++
+ static GVariantSerialised
+ gvs_variable_sized_array_get_child (GVariantSerialised value,
+                                     gsize              index_)
+@@ -708,6 +739,49 @@ gvs_variable_sized_array_get_child (GVariantSerialised value,
+   g_variant_type_info_ref (child.type_info);
+   child.depth = value.depth + 1;
+ 
++  /* If the requested @index_ is beyond the set of indices whose framing offsets
++   * have been checked, check the remaining offsets to see whether they’re
++   * normal (in order, no overlapping array elements). */
++  if (index_ > value.ordered_offsets_up_to)
++    {
++      switch (offsets.offset_size)
++        {
++        case 1:
++          {
++            value.ordered_offsets_up_to = find_unordered_guint8 (
++                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++            break;
++          }
++        case 2:
++          {
++            value.ordered_offsets_up_to = find_unordered_guint16 (
++                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++            break;
++          }
++        case 4:
++          {
++            value.ordered_offsets_up_to = find_unordered_guint32 (
++                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++            break;
++          }
++        case 8:
++          {
++            value.ordered_offsets_up_to = find_unordered_guint64 (
++                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++            break;
++          }
++        default:
++          /* gvs_get_offset_size() only returns maximum 8 */
++          g_assert_not_reached ();
++        }
++    }
++
++  if (index_ > value.ordered_offsets_up_to)
++    {
++      /* Offsets are invalid somewhere, so return an empty child. */
++      return child;
++    }
++
+   if (index_ > 0)
+     {
+       guint alignment;
+@@ -842,6 +916,9 @@ gvs_variable_sized_array_is_normal (GVariantSerialised value)
+ 
+   g_assert (offset == offsets.data_size);
+ 
++  /* All offsets have now been checked. */
++  value.ordered_offsets_up_to = G_MAXSIZE;
++
+   return TRUE;
+ }
+ 
+@@ -1074,7 +1151,7 @@ gvs_tuple_is_normal (GVariantSerialised value)
+   for (i = 0; i < length; i++)
+     {
+       const GVariantMemberInfo *member_info;
+-      GVariantSerialised child;
++      GVariantSerialised child = { 0, };
+       gsize fixed_size;
+       guint alignment;
+       gsize end;
+@@ -1134,6 +1211,9 @@ gvs_tuple_is_normal (GVariantSerialised value)
+       offset = end;
+     }
+ 
++  /* All element bounds have been checked above. */
++  value.ordered_offsets_up_to = G_MAXSIZE;
++
+   {
+     gsize fixed_size;
+     guint alignment;
+diff --git a/glib/gvariant-serialiser.h b/glib/gvariant-serialiser.h
+index 6ced7e3d6c..a1bccb834b 100644
+--- a/glib/gvariant-serialiser.h
++++ b/glib/gvariant-serialiser.h
+@@ -31,6 +31,15 @@ typedef struct
+   guchar           *data;
+   gsize             size;
+   gsize             depth;  /* same semantics as GVariant.depth */
++
++  /* If ordered_offsets_up_to == n this means that all the frame offsets up to and
++   * including the frame offset determining the end of element n are in order.
++   * This guarantees that the bytes of element n don't overlap with any previous
++   * element.
++   *
++   * This is both read and set by g_variant_serialised_get_child for arrays of
++   * non-fixed-width types */
++  gsize             ordered_offsets_up_to;
+ } GVariantSerialised;
+ 
+ /* deserialization */
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index 1a57dc6ef7..c759e8d701 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -1,5 +1,6 @@
+ /*
+  * Copyright © 2010 Codethink Limited
++ * Copyright © 2020 William Manley
+  *
+  * SPDX-License-Identifier: LGPL-2.1-or-later
+  *
+@@ -1281,6 +1282,7 @@ random_instance_filler (GVariantSerialised *serialised,
+     serialised->size = instance->size;
+ 
+   serialised->depth = 0;
++  serialised->ordered_offsets_up_to = 0;
+ 
+   g_assert_true (serialised->type_info == instance->type_info);
+   g_assert_cmpuint (serialised->size, ==, instance->size);
+@@ -5131,6 +5133,47 @@ test_normal_checking_array_offsets (void)
+   g_variant_unref (variant);
+ }
+ 
++/* This is a regression test that we can't have non-normal values that take up
++ * significantly more space than the normal equivalent, by specifying the
++ * offset table entries so that array elements overlap.
++ *
++ * See https://gitlab.gnome.org/GNOME/glib/-/issues/2121#note_832242 */
++static void
++test_normal_checking_array_offsets2 (void)
++{
++  const guint8 data[] = {
++    'h', 'i', '\0',
++    0x03, 0x00, 0x03,
++    0x06, 0x00, 0x06,
++    0x09, 0x00, 0x09,
++    0x0c, 0x00, 0x0c,
++    0x0f, 0x00, 0x0f,
++    0x12, 0x00, 0x12,
++    0x15, 0x00, 0x15,
++  };
++  gsize size = sizeof (data);
++  const GVariantType *aaaaaaas = G_VARIANT_TYPE ("aaaaaaas");
++  GVariant *variant = NULL;
++  GVariant *normal_variant = NULL;
++  GVariant *expected = NULL;
++
++  variant = g_variant_new_from_data (aaaaaaas, data, size, FALSE, NULL, NULL);
++  g_assert_nonnull (variant);
++
++  normal_variant = g_variant_get_normal_form (variant);
++  g_assert_nonnull (normal_variant);
++  g_assert_cmpuint (g_variant_get_size (normal_variant), <=, size * 2);
++
++  expected = g_variant_new_parsed (
++      "[[[[[[['hi', '', ''], [], []], [], []], [], []], [], []], [], []], [], []]");
++  g_assert_cmpvariant (expected, variant);
++  g_assert_cmpvariant (expected, normal_variant);
++
++  g_variant_unref (expected);
++  g_variant_unref (normal_variant);
++  g_variant_unref (variant);
++}
++
+ /* Test that a tuple with invalidly large values in its offset table is
+  * normalised successfully without looping infinitely. */
+ static void
+@@ -5299,6 +5342,8 @@ main (int argc, char **argv)
+                    test_normal_checking_tuples);
+   g_test_add_func ("/gvariant/normal-checking/array-offsets",
+                    test_normal_checking_array_offsets);
++  g_test_add_func ("/gvariant/normal-checking/array-offsets2",
++                   test_normal_checking_array_offsets2);
+   g_test_add_func ("/gvariant/normal-checking/tuple-offsets",
+                    test_normal_checking_tuple_offsets);
+   g_test_add_func ("/gvariant/normal-checking/empty-object-path",
+-- 
+GitLab
+
+
+From 66e7c10aa1ec3102c49186f83671a5f0461ffbc0 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Fri, 7 Jan 2022 15:03:52 +0000
+Subject: [PATCH 05/18] gvariant-serialiser: Factor out code to get bounds of a
+ tuple member
+
+This introduces no functional changes.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2121
+---
+ glib/gvariant-serialiser.c | 73 ++++++++++++++++++++++++--------------
+ 1 file changed, 46 insertions(+), 27 deletions(-)
+
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index 1aa2b8fa9b..a518117e3c 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -944,6 +944,51 @@ gvs_variable_sized_array_is_normal (GVariantSerialised value)
+  * for the tuple.  See the notes in gvarianttypeinfo.h.
+  */
+ 
++static void
++gvs_tuple_get_member_bounds (GVariantSerialised  value,
++                             gsize               index_,
++                             gsize               offset_size,
++                             gsize              *out_member_start,
++                             gsize              *out_member_end)
++{
++  const GVariantMemberInfo *member_info;
++  gsize member_start, member_end;
++
++  member_info = g_variant_type_info_member_info (value.type_info, index_);
++
++  if (member_info->i + 1)
++    member_start = gvs_read_unaligned_le (value.data + value.size -
++                                          offset_size * (member_info->i + 1),
++                                          offset_size);
++  else
++    member_start = 0;
++
++  member_start += member_info->a;
++  member_start &= member_info->b;
++  member_start |= member_info->c;
++
++  if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_LAST)
++    member_end = value.size - offset_size * (member_info->i + 1);
++
++  else if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_FIXED)
++    {
++      gsize fixed_size;
++
++      g_variant_type_info_query (member_info->type_info, NULL, &fixed_size);
++      member_end = member_start + fixed_size;
++    }
++
++  else /* G_VARIANT_MEMBER_ENDING_OFFSET */
++    member_end = gvs_read_unaligned_le (value.data + value.size -
++                                        offset_size * (member_info->i + 2),
++                                        offset_size);
++
++  if (out_member_start != NULL)
++    *out_member_start = member_start;
++  if (out_member_end != NULL)
++    *out_member_end = member_end;
++}
++
+ static gsize
+ gvs_tuple_n_children (GVariantSerialised value)
+ {
+@@ -999,33 +1044,7 @@ gvs_tuple_get_child (GVariantSerialised value,
+         }
+     }
+ 
+-  if (member_info->i + 1)
+-    start = gvs_read_unaligned_le (value.data + value.size -
+-                                   offset_size * (member_info->i + 1),
+-                                   offset_size);
+-  else
+-    start = 0;
+-
+-  start += member_info->a;
+-  start &= member_info->b;
+-  start |= member_info->c;
+-
+-  if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_LAST)
+-    end = value.size - offset_size * (member_info->i + 1);
+-
+-  else if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_FIXED)
+-    {
+-      gsize fixed_size;
+-
+-      g_variant_type_info_query (child.type_info, NULL, &fixed_size);
+-      end = start + fixed_size;
+-      child.size = fixed_size;
+-    }
+-
+-  else /* G_VARIANT_MEMBER_ENDING_OFFSET */
+-    end = gvs_read_unaligned_le (value.data + value.size -
+-                                 offset_size * (member_info->i + 2),
+-                                 offset_size);
++  gvs_tuple_get_member_bounds (value, index_, offset_size, &start, &end);
+ 
+   /* The child should not extend into the offset table. */
+   if (index_ != g_variant_type_info_n_members (value.type_info) - 1)
+-- 
+GitLab
+
+
+From a62a6b5d3e53b30a4628db2a077ab9ed03605748 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Fri, 7 Jan 2022 16:37:29 +0000
+Subject: [PATCH 06/18] gvariant-serialiser: Rework child size calculation
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This reduces a few duplicate calls to `g_variant_type_info_query()` and
+explains why they’re needed.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2121
+---
+ glib/gvariant-serialiser.c | 31 +++++++++----------------------
+ 1 file changed, 9 insertions(+), 22 deletions(-)
+
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index a518117e3c..d32e255480 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -1009,14 +1009,18 @@ gvs_tuple_get_child (GVariantSerialised value,
+   child.depth = value.depth + 1;
+   offset_size = gvs_get_offset_size (value.size);
+ 
++  /* Ensure the size is set for fixed-sized children, or
++   * g_variant_serialised_check() will fail, even if we return
++   * (child.data == NULL) to indicate an error. */
++  if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_FIXED)
++    g_variant_type_info_query (child.type_info, NULL, &child.size);
++
+   /* tuples are the only (potentially) fixed-sized containers, so the
+    * only ones that have to deal with the possibility of having %NULL
+    * data with a non-zero %size if errors occurred elsewhere.
+    */
+   if G_UNLIKELY (value.data == NULL && value.size != 0)
+     {
+-      g_variant_type_info_query (child.type_info, NULL, &child.size);
+-
+       /* this can only happen in fixed-sized tuples,
+        * so the child must also be fixed sized.
+        */
+@@ -1034,29 +1038,12 @@ gvs_tuple_get_child (GVariantSerialised value,
+   else
+     {
+       if (offset_size * (member_info->i + 1) > value.size)
+-        {
+-          /* if the child is fixed size, return its size.
+-           * if child is not fixed-sized, return size = 0.
+-           */
+-          g_variant_type_info_query (child.type_info, NULL, &child.size);
+-
+-          return child;
+-        }
++        return child;
+     }
+ 
+-  gvs_tuple_get_member_bounds (value, index_, offset_size, &start, &end);
+-
+   /* The child should not extend into the offset table. */
+-  if (index_ != g_variant_type_info_n_members (value.type_info) - 1)
+-    {
+-      GVariantSerialised last_child;
+-      last_child = gvs_tuple_get_child (value,
+-                                        g_variant_type_info_n_members (value.type_info) - 1);
+-      last_end = last_child.data + last_child.size - value.data;
+-      g_variant_type_info_unref (last_child.type_info);
+-    }
+-  else
+-    last_end = end;
++  gvs_tuple_get_member_bounds (value, index_, offset_size, &start, &end);
++  gvs_tuple_get_member_bounds (value, g_variant_type_info_n_members (value.type_info) - 1, offset_size, NULL, &last_end);
+ 
+   if (start < end && end <= value.size && end <= last_end)
+     {
+-- 
+GitLab
+
+
+From 2d55b3b74b1bc256e91a9d0d59120570376e6acc Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Fri, 7 Jan 2022 16:42:14 +0000
+Subject: [PATCH 07/18] =?UTF-8?q?gvariant:=20Don=E2=80=99t=20allow=20child?=
+ =?UTF-8?q?=20elements=20of=20a=20tuple=20to=20overlap=20each=20other?=
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This is similar to the earlier commit which prevents child elements of a
+variable-sized array from overlapping each other, but this time for
+tuples. It is based heavily on ideas by William Manley.
+
+Tuples are slightly different from variable-sized arrays in that they
+contain a mixture of fixed and variable sized elements. All but one of
+the variable sized elements have an entry in the frame offsets table.
+This means that if we were to just check the ordering of the frame
+offsets table, the variable sized elements could still overlap
+interleaving fixed sized elements, which would be bad.
+
+Therefore we have to check the elements rather than the frame offsets.
+
+The logic of checking the elements up to the index currently being
+requested, and caching the result in `ordered_offsets_up_to`, means that
+the algorithmic cost implications are the same for this commit as for
+variable-sized arrays: an O(N) cost for these checks is amortised out
+over N accesses to O(1) per access.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Fixes: #2121
+---
+ glib/gvariant-core.c       |   6 +-
+ glib/gvariant-serialiser.c |  40 ++++++++
+ glib/gvariant-serialiser.h |   7 +-
+ glib/gvariant.c            |   1 +
+ glib/tests/gvariant.c      | 181 +++++++++++++++++++++++++++++++++++++
+ 5 files changed, 232 insertions(+), 3 deletions(-)
+
+diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
+index a75e7db9ea..c0e1931c39 100644
+--- a/glib/gvariant-core.c
++++ b/glib/gvariant-core.c
+@@ -1,6 +1,7 @@
+ /*
+  * Copyright © 2007, 2008 Ryan Lortie
+  * Copyright © 2010 Codethink Limited
++ * Copyright © 2022 Endless OS Foundation, LLC
+  *
+  * SPDX-License-Identifier: LGPL-2.1-or-later
+  *
+@@ -181,7 +182,7 @@ struct _GVariant
+  *                             offsets themselves.
+  *
+  *                             This field is only relevant for arrays of non
+- *                             fixed width types.
++ *                             fixed width types and for tuples.
+  *
+  *   .tree: Only valid when the instance is in tree form.
+  *
+@@ -1141,6 +1142,9 @@ g_variant_get_child_value (GVariant *value,
+      */
+     s_child = g_variant_serialised_get_child (serialised, index_);
+ 
++    /* Update the cached ordered_offsets_up_to, since @serialised will be thrown away when this function exits */
++    value->contents.serialised.ordered_offsets_up_to = MAX (value->contents.serialised.ordered_offsets_up_to, serialised.ordered_offsets_up_to);
++
+     /* Check whether this would cause nesting too deep. If so, return a fake
+      * child. The only situation we expect this to happen in is with a variant,
+      * as all other deeply-nested types have a static type, and hence should
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index d32e255480..fda59d6843 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -944,6 +944,10 @@ gvs_variable_sized_array_is_normal (GVariantSerialised value)
+  * for the tuple.  See the notes in gvarianttypeinfo.h.
+  */
+ 
++/* Note: This doesn’t guarantee that @out_member_end >= @out_member_start; that
++ * condition may not hold true for invalid serialised variants. The caller is
++ * responsible for checking the returned values and handling invalid ones
++ * appropriately. */
+ static void
+ gvs_tuple_get_member_bounds (GVariantSerialised  value,
+                              gsize               index_,
+@@ -1030,6 +1034,42 @@ gvs_tuple_get_child (GVariantSerialised value,
+       return child;
+     }
+ 
++  /* If the requested @index_ is beyond the set of indices whose framing offsets
++   * have been checked, check the remaining offsets to see whether they’re
++   * normal (in order, no overlapping tuple elements).
++   *
++   * Unlike the checks in gvs_variable_sized_array_get_child(), we have to check
++   * all the tuple *elements* here, not just all the framing offsets, since
++   * tuples contain a mix of elements which use framing offsets and ones which
++   * don’t. None of them are allowed to overlap. */
++  if (index_ > value.ordered_offsets_up_to)
++    {
++      gsize i, prev_i_end = 0;
++
++      if (value.ordered_offsets_up_to > 0)
++        gvs_tuple_get_member_bounds (value, value.ordered_offsets_up_to - 1, offset_size, NULL, &prev_i_end);
++
++      for (i = value.ordered_offsets_up_to; i <= index_; i++)
++        {
++          gsize i_start, i_end;
++
++          gvs_tuple_get_member_bounds (value, i, offset_size, &i_start, &i_end);
++
++          if (i_start > i_end || i_start < prev_i_end || i_end > value.size)
++            break;
++
++          prev_i_end = i_end;
++        }
++
++      value.ordered_offsets_up_to = i - 1;
++    }
++
++  if (index_ > value.ordered_offsets_up_to)
++    {
++      /* Offsets are invalid somewhere, so return an empty child. */
++      return child;
++    }
++
+   if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_OFFSET)
+     {
+       if (offset_size * (member_info->i + 2) > value.size)
+diff --git a/glib/gvariant-serialiser.h b/glib/gvariant-serialiser.h
+index a1bccb834b..661bd8fd1b 100644
+--- a/glib/gvariant-serialiser.h
++++ b/glib/gvariant-serialiser.h
+@@ -37,8 +37,11 @@ typedef struct
+    * This guarantees that the bytes of element n don't overlap with any previous
+    * element.
+    *
+-   * This is both read and set by g_variant_serialised_get_child for arrays of
+-   * non-fixed-width types */
++   * This is both read and set by g_variant_serialised_get_child() for arrays of
++   * non-fixed-width types, and for tuples.
++   *
++   * Even when dealing with tuples, @ordered_offsets_up_to is an element index,
++   * rather than an index into the frame offsets. */
+   gsize             ordered_offsets_up_to;
+ } GVariantSerialised;
+ 
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index 6912eebe05..16af7a5678 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -6010,6 +6010,7 @@ g_variant_byteswap (GVariant *value)
+       serialised.size = g_variant_get_size (trusted);
+       serialised.data = g_malloc (serialised.size);
+       serialised.depth = g_variant_get_depth (trusted);
++      serialised.ordered_offsets_up_to = G_MAXSIZE;  /* operating on the normal form */
+       g_variant_store (trusted, serialised.data);
+       g_variant_unref (trusted);
+ 
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index c759e8d701..0cb69d4b70 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -1,6 +1,7 @@
+ /*
+  * Copyright © 2010 Codethink Limited
+  * Copyright © 2020 William Manley
++ * Copyright © 2022 Endless OS Foundation, LLC
+  *
+  * SPDX-License-Identifier: LGPL-2.1-or-later
+  *
+@@ -1449,6 +1450,7 @@ test_maybe (void)
+         serialised.data = flavoured_malloc (needed_size, flavour);
+         serialised.size = needed_size;
+         serialised.depth = 0;
++        serialised.ordered_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised,
+                                         random_instance_filler,
+@@ -1572,6 +1574,7 @@ test_array (void)
+         serialised.data = flavoured_malloc (needed_size, flavour);
+         serialised.size = needed_size;
+         serialised.depth = 0;
++        serialised.ordered_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised, random_instance_filler,
+                                         (gpointer *) instances, n_children);
+@@ -1736,6 +1739,7 @@ test_tuple (void)
+         serialised.data = flavoured_malloc (needed_size, flavour);
+         serialised.size = needed_size;
+         serialised.depth = 0;
++        serialised.ordered_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised, random_instance_filler,
+                                         (gpointer *) instances, n_children);
+@@ -1832,6 +1836,7 @@ test_variant (void)
+         serialised.data = flavoured_malloc (needed_size, flavour);
+         serialised.size = needed_size;
+         serialised.depth = 0;
++        serialised.ordered_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised, random_instance_filler,
+                                         (gpointer *) &instance, 1);
+@@ -5198,6 +5203,176 @@ test_normal_checking_tuple_offsets (void)
+   g_variant_unref (variant);
+ }
+ 
++/* This is a regression test that we can't have non-normal values that take up
++ * significantly more space than the normal equivalent, by specifying the
++ * offset table entries so that tuple elements overlap.
++ *
++ * See https://gitlab.gnome.org/GNOME/glib/-/issues/2121#note_838503 and
++ * https://gitlab.gnome.org/GNOME/glib/-/issues/2121#note_838513 */
++static void
++test_normal_checking_tuple_offsets2 (void)
++{
++  const GVariantType *data_type = G_VARIANT_TYPE ("(yyaiyyaiyy)");
++  const guint8 data[] = {
++    0x12, 0x34, 0x56, 0x78, 0x01,
++    /*
++         ^───────────────────┘
++
++    ^^^^^^^^^^                   1st yy
++          ^^^^^^^^^^             2nd yy
++                ^^^^^^^^^^       3rd yy
++                            ^^^^ Framing offsets
++     */
++
++  /* If this variant was encoded normally, it would be something like this:
++   * 0x12, 0x34,  pad,  pad, [array bytes], 0x56, 0x78,  pad,  pad, [array bytes], 0x9A, 0xBC, 0xXX
++   *                                      ^─────────────────────────────────────────────────────┘
++   *
++   * ^^^^^^^^^^                                                                                     1st yy
++   *                                        ^^^^^^^^^^                                              2nd yy
++   *                                                                               ^^^^^^^^^^       3rd yy
++   *                                                                                           ^^^^ Framing offsets
++   */
++  };
++  gsize size = sizeof (data);
++  GVariant *variant = NULL;
++  GVariant *normal_variant = NULL;
++  GVariant *expected = NULL;
++
++  variant = g_variant_new_from_data (data_type, data, size, FALSE, NULL, NULL);
++  g_assert_nonnull (variant);
++
++  normal_variant = g_variant_get_normal_form (variant);
++  g_assert_nonnull (normal_variant);
++  g_assert_cmpuint (g_variant_get_size (normal_variant), <=, size * 3);
++
++  expected = g_variant_new_parsed (
++      "@(yyaiyyaiyy) (0x12, 0x34, [], 0x00, 0x00, [], 0x00, 0x00)");
++  g_assert_cmpvariant (expected, variant);
++  g_assert_cmpvariant (expected, normal_variant);
++
++  g_variant_unref (expected);
++  g_variant_unref (normal_variant);
++  g_variant_unref (variant);
++}
++
++/* This is a regression test that overlapping entries in the offset table are
++ * decoded consistently, even though they’re non-normal.
++ *
++ * See https://gitlab.gnome.org/GNOME/glib/-/issues/2121#note_910935 */
++static void
++test_normal_checking_tuple_offsets3 (void)
++{
++  /* The expected decoding of this non-normal byte stream is complex. See
++   * section 2.7.3 (Handling Non-Normal Serialised Data) of the GVariant
++   * specification.
++   *
++   * The rule “Child Values Overlapping Framing Offsets” from the specification
++   * says that the first `ay` must be decoded as `[0x01]` even though it
++   * overlaps the first byte of the offset table. However, since commit
++   * 7eedcd76f7d5b8c98fa60013e1fe6e960bf19df3, GLib explicitly doesn’t allow
++   * this as it’s exploitable. So the first `ay` must be given a default value.
++   *
++   * The second and third `ay`s must be given default values because of rule
++   * “End Boundary Precedes Start Boundary”.
++   *
++   * The `i` must be given a default value because of rule “Start or End
++   * Boundary of a Child Falls Outside the Container”.
++   */
++  const GVariantType *data_type = G_VARIANT_TYPE ("(ayayiay)");
++  const guint8 data[] = {
++    0x01, 0x00, 0x02,
++    /*
++               ^──┘
++
++    ^^^^^^^^^^                   1st ay, bytes 0-2 (but given a default value anyway, see above)
++                                 2nd ay, bytes 2-0
++                                     i,  bytes 0-4
++                                 3rd ay, bytes 4-1
++          ^^^^^^^^^^ Framing offsets
++     */
++  };
++  gsize size = sizeof (data);
++  GVariant *variant = NULL;
++  GVariant *normal_variant = NULL;
++  GVariant *expected = NULL;
++
++  variant = g_variant_new_from_data (data_type, data, size, FALSE, NULL, NULL);
++  g_assert_nonnull (variant);
++
++  g_assert_false (g_variant_is_normal_form (variant));
++
++  normal_variant = g_variant_get_normal_form (variant);
++  g_assert_nonnull (normal_variant);
++  g_assert_cmpuint (g_variant_get_size (normal_variant), <=, size * 3);
++
++  expected = g_variant_new_parsed ("@(ayayiay) ([], [], 0, [])");
++  g_assert_cmpvariant (expected, variant);
++  g_assert_cmpvariant (expected, normal_variant);
++
++  g_variant_unref (expected);
++  g_variant_unref (normal_variant);
++  g_variant_unref (variant);
++}
++
++/* This is a regression test that overlapping entries in the offset table are
++ * decoded consistently, even though they’re non-normal.
++ *
++ * See https://gitlab.gnome.org/GNOME/glib/-/issues/2121#note_910935 */
++static void
++test_normal_checking_tuple_offsets4 (void)
++{
++  /* The expected decoding of this non-normal byte stream is complex. See
++   * section 2.7.3 (Handling Non-Normal Serialised Data) of the GVariant
++   * specification.
++   *
++   * The rule “Child Values Overlapping Framing Offsets” from the specification
++   * says that the first `ay` must be decoded as `[0x01]` even though it
++   * overlaps the first byte of the offset table. However, since commit
++   * 7eedcd76f7d5b8c98fa60013e1fe6e960bf19df3, GLib explicitly doesn’t allow
++   * this as it’s exploitable. So the first `ay` must be given a default value.
++   *
++   * The second `ay` must be given a default value because of rule “End Boundary
++   * Precedes Start Boundary”.
++   *
++   * The third `ay` must be given a default value because its framing offsets
++   * overlap that of the first `ay`.
++   */
++  const GVariantType *data_type = G_VARIANT_TYPE ("(ayayay)");
++  const guint8 data[] = {
++    0x01, 0x00, 0x02,
++    /*
++               ^──┘
++
++    ^^^^^^^^^^                   1st ay, bytes 0-2 (but given a default value anyway, see above)
++                                 2nd ay, bytes 2-0
++                                 3rd ay, bytes 0-1
++          ^^^^^^^^^^ Framing offsets
++     */
++  };
++  gsize size = sizeof (data);
++  GVariant *variant = NULL;
++  GVariant *normal_variant = NULL;
++  GVariant *expected = NULL;
++
++  variant = g_variant_new_from_data (data_type, data, size, FALSE, NULL, NULL);
++  g_assert_nonnull (variant);
++
++  g_assert_false (g_variant_is_normal_form (variant));
++
++  normal_variant = g_variant_get_normal_form (variant);
++  g_assert_nonnull (normal_variant);
++  g_assert_cmpuint (g_variant_get_size (normal_variant), <=, size * 3);
++
++  expected = g_variant_new_parsed ("@(ayayay) ([], [], [])");
++  g_assert_cmpvariant (expected, variant);
++  g_assert_cmpvariant (expected, normal_variant);
++
++  g_variant_unref (expected);
++  g_variant_unref (normal_variant);
++  g_variant_unref (variant);
++}
++
+ /* Test that an empty object path is normalised successfully to the base object
+  * path, ‘/’. */
+ static void
+@@ -5346,6 +5521,12 @@ main (int argc, char **argv)
+                    test_normal_checking_array_offsets2);
+   g_test_add_func ("/gvariant/normal-checking/tuple-offsets",
+                    test_normal_checking_tuple_offsets);
++  g_test_add_func ("/gvariant/normal-checking/tuple-offsets2",
++                   test_normal_checking_tuple_offsets2);
++  g_test_add_func ("/gvariant/normal-checking/tuple-offsets3",
++                   test_normal_checking_tuple_offsets3);
++  g_test_add_func ("/gvariant/normal-checking/tuple-offsets4",
++                   test_normal_checking_tuple_offsets4);
+   g_test_add_func ("/gvariant/normal-checking/empty-object-path",
+                    test_normal_checking_empty_object_path);
+ 
+-- 
+GitLab
+
+
+From a6cb880af0a0932493ba096f01990e694e2c5b72 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Tue, 25 Oct 2022 15:14:14 +0100
+Subject: [PATCH 08/18] gvariant: Track checked and ordered offsets
+ independently
+
+The past few commits introduced the concept of known-good offsets in the
+offset table (which is used for variable-width arrays and tuples).
+Good offsets are ones which are non-overlapping with all the previous
+offsets in the table.
+
+If a bad offset is encountered when indexing into the array or tuple,
+the cached known-good offset index will not be increased. In this way,
+all child variants at and beyond the first bad offset can be returned as
+default values rather than dereferencing potentially invalid data.
+
+In this case, there was no information about the fact that the indexes
+between the highest known-good index and the requested one had been
+checked already. That could lead to a pathological case where an offset
+table with an invalid first offset is repeatedly checked in full when
+trying to access higher-indexed children.
+
+Avoid that by storing the index of the highest checked offset in the
+table, as well as the index of the highest good/ordered offset.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2121
+---
+ glib/gvariant-core.c       | 28 ++++++++++++++++++++++++
+ glib/gvariant-serialiser.c | 44 +++++++++++++++++++++++++++-----------
+ glib/gvariant-serialiser.h |  9 ++++++++
+ glib/gvariant.c            |  1 +
+ glib/tests/gvariant.c      |  5 +++++
+ 5 files changed, 75 insertions(+), 12 deletions(-)
+
+diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
+index c0e1931c39..e61242f763 100644
+--- a/glib/gvariant-core.c
++++ b/glib/gvariant-core.c
+@@ -69,6 +69,7 @@ struct _GVariant
+       GBytes *bytes;
+       gconstpointer data;
+       gsize ordered_offsets_up_to;
++      gsize checked_offsets_up_to;
+     } serialised;
+ 
+     struct
+@@ -184,6 +185,24 @@ struct _GVariant
+  *                             This field is only relevant for arrays of non
+  *                             fixed width types and for tuples.
+  *
++ *     .checked_offsets_up_to: Similarly to .ordered_offsets_up_to, this stores
++ *                             the index of the highest element, n, whose frame
++ *                             offsets (and all the preceding frame offsets)
++ *                             have been checked for validity.
++ *
++ *                             It is always the case that
++ *                             .checked_offsets_up_to ≥ .ordered_offsets_up_to.
++ *
++ *                             If .checked_offsets_up_to == .ordered_offsets_up_to,
++ *                             then a bad offset has not been found so far.
++ *
++ *                             If .checked_offsets_up_to > .ordered_offsets_up_to,
++ *                             then a bad offset has been found at
++ *                             (.ordered_offsets_up_to + 1).
++ *
++ *                             This field is only relevant for arrays of non
++ *                             fixed width types and for tuples.
++ *
+  *   .tree: Only valid when the instance is in tree form.
+  *
+  *          Note that accesses from other threads could result in
+@@ -388,6 +407,7 @@ g_variant_to_serialised (GVariant *value)
+       value->size,
+       value->depth,
+       value->contents.serialised.ordered_offsets_up_to,
++      value->contents.serialised.checked_offsets_up_to,
+     };
+     return serialised;
+   }
+@@ -420,6 +440,7 @@ g_variant_serialise (GVariant *value,
+   serialised.data = data;
+   serialised.depth = value->depth;
+   serialised.ordered_offsets_up_to = 0;
++  serialised.checked_offsets_up_to = 0;
+ 
+   children = (gpointer *) value->contents.tree.children;
+   n_children = value->contents.tree.n_children;
+@@ -466,10 +487,12 @@ g_variant_fill_gvs (GVariantSerialised *serialised,
+   if (value->state & STATE_SERIALISED)
+     {
+       serialised->ordered_offsets_up_to = value->contents.serialised.ordered_offsets_up_to;
++      serialised->checked_offsets_up_to = value->contents.serialised.checked_offsets_up_to;
+     }
+   else
+     {
+       serialised->ordered_offsets_up_to = 0;
++      serialised->checked_offsets_up_to = 0;
+     }
+ 
+   if (serialised->data)
+@@ -515,6 +538,7 @@ g_variant_ensure_serialised (GVariant *value)
+       value->contents.serialised.data = g_bytes_get_data (bytes, NULL);
+       value->contents.serialised.bytes = bytes;
+       value->contents.serialised.ordered_offsets_up_to = G_MAXSIZE;
++      value->contents.serialised.checked_offsets_up_to = G_MAXSIZE;
+       value->state |= STATE_SERIALISED;
+     }
+ }
+@@ -596,6 +620,7 @@ g_variant_new_from_bytes (const GVariantType *type,
+   serialised.data = (guchar *) g_bytes_get_data (bytes, &serialised.size);
+   serialised.depth = 0;
+   serialised.ordered_offsets_up_to = trusted ? G_MAXSIZE : 0;
++  serialised.checked_offsets_up_to = trusted ? G_MAXSIZE : 0;
+ 
+   if (!g_variant_serialised_check (serialised))
+     {
+@@ -647,6 +672,7 @@ g_variant_new_from_bytes (const GVariantType *type,
+     }
+ 
+   value->contents.serialised.ordered_offsets_up_to = trusted ? G_MAXSIZE : 0;
++  value->contents.serialised.checked_offsets_up_to = trusted ? G_MAXSIZE : 0;
+ 
+   g_clear_pointer (&owned_bytes, g_bytes_unref);
+ 
+@@ -1144,6 +1170,7 @@ g_variant_get_child_value (GVariant *value,
+ 
+     /* Update the cached ordered_offsets_up_to, since @serialised will be thrown away when this function exits */
+     value->contents.serialised.ordered_offsets_up_to = MAX (value->contents.serialised.ordered_offsets_up_to, serialised.ordered_offsets_up_to);
++    value->contents.serialised.checked_offsets_up_to = MAX (value->contents.serialised.checked_offsets_up_to, serialised.checked_offsets_up_to);
+ 
+     /* Check whether this would cause nesting too deep. If so, return a fake
+      * child. The only situation we expect this to happen in is with a variant,
+@@ -1171,6 +1198,7 @@ g_variant_get_child_value (GVariant *value,
+       g_bytes_ref (value->contents.serialised.bytes);
+     child->contents.serialised.data = s_child.data;
+     child->contents.serialised.ordered_offsets_up_to = s_child.ordered_offsets_up_to;
++    child->contents.serialised.checked_offsets_up_to = s_child.checked_offsets_up_to;
+ 
+     return child;
+   }
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index fda59d6843..591522a2e1 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -122,6 +122,8 @@
+  *
+  * @depth has no restrictions; the depth of a top-level serialized #GVariant is
+  * zero, and it increases for each level of nested child.
++ *
++ * @checked_offsets_up_to is always ≥ @ordered_offsets_up_to
+  */
+ 
+ /* < private >
+@@ -149,6 +151,9 @@ g_variant_serialised_check (GVariantSerialised serialised)
+            !(serialised.size == 0 || serialised.data != NULL))
+     return FALSE;
+ 
++  if (serialised.ordered_offsets_up_to > serialised.checked_offsets_up_to)
++    return FALSE;
++
+   /* Depending on the native alignment requirements of the machine, the
+    * compiler will insert either 3 or 7 padding bytes after the char.
+    * This will result in the sizeof() the struct being 12 or 16.
+@@ -268,6 +273,7 @@ gvs_fixed_sized_maybe_get_child (GVariantSerialised value,
+   g_variant_type_info_ref (value.type_info);
+   value.depth++;
+   value.ordered_offsets_up_to = 0;
++  value.checked_offsets_up_to = 0;
+ 
+   return value;
+ }
+@@ -299,7 +305,7 @@ gvs_fixed_sized_maybe_serialise (GVariantSerialised        value,
+ {
+   if (n_children)
+     {
+-      GVariantSerialised child = { NULL, value.data, value.size, value.depth + 1, 0 };
++      GVariantSerialised child = { NULL, value.data, value.size, value.depth + 1, 0, 0 };
+ 
+       gvs_filler (&child, children[0]);
+     }
+@@ -322,6 +328,7 @@ gvs_fixed_sized_maybe_is_normal (GVariantSerialised value)
+       value.type_info = g_variant_type_info_element (value.type_info);
+       value.depth++;
+       value.ordered_offsets_up_to = 0;
++      value.checked_offsets_up_to = 0;
+ 
+       return g_variant_serialised_is_normal (value);
+     }
+@@ -364,6 +371,7 @@ gvs_variable_sized_maybe_get_child (GVariantSerialised value,
+ 
+   value.depth++;
+   value.ordered_offsets_up_to = 0;
++  value.checked_offsets_up_to = 0;
+ 
+   return value;
+ }
+@@ -394,7 +402,7 @@ gvs_variable_sized_maybe_serialise (GVariantSerialised        value,
+ {
+   if (n_children)
+     {
+-      GVariantSerialised child = { NULL, value.data, value.size - 1, value.depth + 1, 0 };
++      GVariantSerialised child = { NULL, value.data, value.size - 1, value.depth + 1, 0, 0 };
+ 
+       /* write the data for the child.  */
+       gvs_filler (&child, children[0]);
+@@ -415,6 +423,7 @@ gvs_variable_sized_maybe_is_normal (GVariantSerialised value)
+   value.size--;
+   value.depth++;
+   value.ordered_offsets_up_to = 0;
++  value.checked_offsets_up_to = 0;
+ 
+   return g_variant_serialised_is_normal (value);
+ }
+@@ -741,39 +750,46 @@ gvs_variable_sized_array_get_child (GVariantSerialised value,
+ 
+   /* If the requested @index_ is beyond the set of indices whose framing offsets
+    * have been checked, check the remaining offsets to see whether they’re
+-   * normal (in order, no overlapping array elements). */
+-  if (index_ > value.ordered_offsets_up_to)
++   * normal (in order, no overlapping array elements).
++   *
++   * Don’t bother checking if the highest known-good offset is lower than the
++   * highest checked offset, as that means there’s an invalid element at that
++   * index, so there’s no need to check further. */
++  if (index_ > value.checked_offsets_up_to &&
++      value.ordered_offsets_up_to == value.checked_offsets_up_to)
+     {
+       switch (offsets.offset_size)
+         {
+         case 1:
+           {
+             value.ordered_offsets_up_to = find_unordered_guint8 (
+-                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++                offsets.array, value.checked_offsets_up_to, index_ + 1);
+             break;
+           }
+         case 2:
+           {
+             value.ordered_offsets_up_to = find_unordered_guint16 (
+-                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++                offsets.array, value.checked_offsets_up_to, index_ + 1);
+             break;
+           }
+         case 4:
+           {
+             value.ordered_offsets_up_to = find_unordered_guint32 (
+-                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++                offsets.array, value.checked_offsets_up_to, index_ + 1);
+             break;
+           }
+         case 8:
+           {
+             value.ordered_offsets_up_to = find_unordered_guint64 (
+-                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++                offsets.array, value.checked_offsets_up_to, index_ + 1);
+             break;
+           }
+         default:
+           /* gvs_get_offset_size() only returns maximum 8 */
+           g_assert_not_reached ();
+         }
++
++      value.checked_offsets_up_to = index_;
+     }
+ 
+   if (index_ > value.ordered_offsets_up_to)
+@@ -918,6 +934,7 @@ gvs_variable_sized_array_is_normal (GVariantSerialised value)
+ 
+   /* All offsets have now been checked. */
+   value.ordered_offsets_up_to = G_MAXSIZE;
++  value.checked_offsets_up_to = G_MAXSIZE;
+ 
+   return TRUE;
+ }
+@@ -1042,14 +1059,15 @@ gvs_tuple_get_child (GVariantSerialised value,
+    * all the tuple *elements* here, not just all the framing offsets, since
+    * tuples contain a mix of elements which use framing offsets and ones which
+    * don’t. None of them are allowed to overlap. */
+-  if (index_ > value.ordered_offsets_up_to)
++  if (index_ > value.checked_offsets_up_to &&
++      value.ordered_offsets_up_to == value.checked_offsets_up_to)
+     {
+       gsize i, prev_i_end = 0;
+ 
+-      if (value.ordered_offsets_up_to > 0)
+-        gvs_tuple_get_member_bounds (value, value.ordered_offsets_up_to - 1, offset_size, NULL, &prev_i_end);
++      if (value.checked_offsets_up_to > 0)
++        gvs_tuple_get_member_bounds (value, value.checked_offsets_up_to - 1, offset_size, NULL, &prev_i_end);
+ 
+-      for (i = value.ordered_offsets_up_to; i <= index_; i++)
++      for (i = value.checked_offsets_up_to; i <= index_; i++)
+         {
+           gsize i_start, i_end;
+ 
+@@ -1062,6 +1080,7 @@ gvs_tuple_get_child (GVariantSerialised value,
+         }
+ 
+       value.ordered_offsets_up_to = i - 1;
++      value.checked_offsets_up_to = index_;
+     }
+ 
+   if (index_ > value.ordered_offsets_up_to)
+@@ -1259,6 +1278,7 @@ gvs_tuple_is_normal (GVariantSerialised value)
+ 
+   /* All element bounds have been checked above. */
+   value.ordered_offsets_up_to = G_MAXSIZE;
++  value.checked_offsets_up_to = G_MAXSIZE;
+ 
+   {
+     gsize fixed_size;
+diff --git a/glib/gvariant-serialiser.h b/glib/gvariant-serialiser.h
+index 661bd8fd1b..eb74fe7804 100644
+--- a/glib/gvariant-serialiser.h
++++ b/glib/gvariant-serialiser.h
+@@ -43,6 +43,15 @@ typedef struct
+    * Even when dealing with tuples, @ordered_offsets_up_to is an element index,
+    * rather than an index into the frame offsets. */
+   gsize             ordered_offsets_up_to;
++
++  /* Similar to @ordered_offsets_up_to. This gives the index of the child element
++   * whose frame offset is the highest in the offset table which has been
++   * checked so far.
++   *
++   * This is always ≥ @ordered_offsets_up_to. It is always an element index.
++   *
++   * See documentation in gvariant-core.c for `struct GVariant` for details. */
++  gsize             checked_offsets_up_to;
+ } GVariantSerialised;
+ 
+ /* deserialization */
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index 16af7a5678..48e49490ba 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -6011,6 +6011,7 @@ g_variant_byteswap (GVariant *value)
+       serialised.data = g_malloc (serialised.size);
+       serialised.depth = g_variant_get_depth (trusted);
+       serialised.ordered_offsets_up_to = G_MAXSIZE;  /* operating on the normal form */
++      serialised.checked_offsets_up_to = G_MAXSIZE;
+       g_variant_store (trusted, serialised.data);
+       g_variant_unref (trusted);
+ 
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index 0cb69d4b70..941e58f1bc 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -1284,6 +1284,7 @@ random_instance_filler (GVariantSerialised *serialised,
+ 
+   serialised->depth = 0;
+   serialised->ordered_offsets_up_to = 0;
++  serialised->checked_offsets_up_to = 0;
+ 
+   g_assert_true (serialised->type_info == instance->type_info);
+   g_assert_cmpuint (serialised->size, ==, instance->size);
+@@ -1451,6 +1452,7 @@ test_maybe (void)
+         serialised.size = needed_size;
+         serialised.depth = 0;
+         serialised.ordered_offsets_up_to = 0;
++        serialised.checked_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised,
+                                         random_instance_filler,
+@@ -1575,6 +1577,7 @@ test_array (void)
+         serialised.size = needed_size;
+         serialised.depth = 0;
+         serialised.ordered_offsets_up_to = 0;
++        serialised.checked_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised, random_instance_filler,
+                                         (gpointer *) instances, n_children);
+@@ -1740,6 +1743,7 @@ test_tuple (void)
+         serialised.size = needed_size;
+         serialised.depth = 0;
+         serialised.ordered_offsets_up_to = 0;
++        serialised.checked_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised, random_instance_filler,
+                                         (gpointer *) instances, n_children);
+@@ -1837,6 +1841,7 @@ test_variant (void)
+         serialised.size = needed_size;
+         serialised.depth = 0;
+         serialised.ordered_offsets_up_to = 0;
++        serialised.checked_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised, random_instance_filler,
+                                         (gpointer *) &instance, 1);
+-- 
+GitLab
+
+
+From 8c1a7815e7e6695c120cdedff48395c1222af6d1 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <withnall@endlessm.com>
+Date: Fri, 12 Jun 2020 18:01:13 +0100
+Subject: [PATCH 09/18] tests: Add another test for overlapping offsets in
+ GVariant
+
+Signed-off-by: Philip Withnall <withnall@endlessm.com>
+
+Helps: #2121
+---
+ glib/tests/gvariant.c | 34 ++++++++++++++++++++++++++++++++++
+ 1 file changed, 34 insertions(+)
+
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index 941e58f1bc..867cb5b9b4 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -5119,6 +5119,38 @@ test_recursion_limits_array_in_variant (void)
+   g_variant_unref (wrapper_variant);
+ }
+ 
++/* Test that a nested array with invalid values in its offset table (which point
++ * from the inner to the outer array) is normalised successfully without
++ * looping infinitely. */
++static void
++test_normal_checking_array_offsets_overlapped (void)
++{
++  const guint8 data[] = {
++    0x01, 0x00,
++  };
++  gsize size = sizeof (data);
++  GVariant *variant = NULL;
++  GVariant *normal_variant = NULL;
++  GVariant *expected_variant = NULL;
++
++  variant = g_variant_new_from_data (G_VARIANT_TYPE ("aay"), data, size,
++                                     FALSE, NULL, NULL);
++  g_assert_nonnull (variant);
++
++  normal_variant = g_variant_get_normal_form (variant);
++  g_assert_nonnull (normal_variant);
++
++  expected_variant = g_variant_new_parsed ("[@ay [], []]");
++  g_assert_cmpvariant (normal_variant, expected_variant);
++
++  g_assert_cmpmem (g_variant_get_data (normal_variant), g_variant_get_size (normal_variant),
++                   g_variant_get_data (expected_variant), g_variant_get_size (expected_variant));
++
++  g_variant_unref (expected_variant);
++  g_variant_unref (normal_variant);
++  g_variant_unref (variant);
++}
++
+ /* Test that an array with invalidly large values in its offset table is
+  * normalised successfully without looping infinitely. */
+ static void
+@@ -5520,6 +5552,8 @@ main (int argc, char **argv)
+ 
+   g_test_add_func ("/gvariant/normal-checking/tuples",
+                    test_normal_checking_tuples);
++  g_test_add_func ("/gvariant/normal-checking/array-offsets/overlapped",
++                   test_normal_checking_array_offsets_overlapped);
+   g_test_add_func ("/gvariant/normal-checking/array-offsets",
+                    test_normal_checking_array_offsets);
+   g_test_add_func ("/gvariant/normal-checking/array-offsets2",
+-- 
+GitLab
+
+
+From 019505a7ccc32d0afa06e104dc0ac2e63e6f7189 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Mon, 24 Oct 2022 16:43:23 +0100
+Subject: [PATCH 10/18] tests: Disable some random instance tests of GVariants
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Building a `GVariant` using entirely random data may result in a
+non-normally-formed `GVariant`. It’s always possible to read these
+`GVariant`s, but the API might return default values for some or all of
+their components.
+
+In particular, this can easily happen when randomly generating the
+offset tables for non-fixed-width container types.
+
+If it does happen, bytewise comparison of the parsed `GVariant` with the
+original bytes will not always match. So skip those checks.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2121
+---
+ glib/tests/gvariant.c | 12 +++++++++---
+ 1 file changed, 9 insertions(+), 3 deletions(-)
+
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index 867cb5b9b4..9739993e66 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -1231,6 +1231,7 @@ random_instance_assert (RandomInstance *instance,
+   GRand *rand;
+   gsize i;
+ 
++  g_assert_true (size == 0 || buffer != NULL);
+   g_assert_cmpint ((gsize) buffer & ALIGN_BITS & instance->alignment, ==, 0);
+   g_assert_cmpint (size, ==, instance->size);
+ 
+@@ -1457,10 +1458,13 @@ test_maybe (void)
+         g_variant_serialiser_serialise (serialised,
+                                         random_instance_filler,
+                                         (gpointer *) &instance, 1);
++
+         child = g_variant_serialised_get_child (serialised, 0);
+         g_assert_true (child.type_info == instance->type_info);
+-        random_instance_assert (instance, child.data, child.size);
++        if (child.data != NULL)  /* could be NULL if element is non-normal */
++          random_instance_assert (instance, child.data, child.size);
+         g_variant_type_info_unref (child.type_info);
++
+         flavoured_free (serialised.data, flavour);
+       }
+   }
+@@ -1593,7 +1597,8 @@ test_array (void)
+ 
+             child = g_variant_serialised_get_child (serialised, i);
+             g_assert_true (child.type_info == instances[i]->type_info);
+-            random_instance_assert (instances[i], child.data, child.size);
++            if (child.data != NULL)  /* could be NULL if element is non-normal */
++              random_instance_assert (instances[i], child.data, child.size);
+             g_variant_type_info_unref (child.type_info);
+           }
+ 
+@@ -1759,7 +1764,8 @@ test_tuple (void)
+ 
+             child = g_variant_serialised_get_child (serialised, i);
+             g_assert_true (child.type_info == instances[i]->type_info);
+-            random_instance_assert (instances[i], child.data, child.size);
++            if (child.data != NULL)  /* could be NULL if element is non-normal */
++              random_instance_assert (instances[i], child.data, child.size);
+             g_variant_type_info_unref (child.type_info);
+           }
+ 
+-- 
+GitLab
+
+
+From 9d2a142807806212a23436d0332b0209733810f2 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Mon, 24 Oct 2022 18:14:57 +0100
+Subject: [PATCH 11/18] gvariant: Clarify the docs for
+ g_variant_get_normal_form()
+
+Document how non-normal parts of the `GVariant` are handled.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+---
+ glib/gvariant.c | 4 +++-
+ 1 file changed, 3 insertions(+), 1 deletion(-)
+
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index 48e49490ba..e92564eb64 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -5936,7 +5936,9 @@ g_variant_deep_copy (GVariant *value)
+  * marked as trusted and a new reference to it is returned.
+  *
+  * If @value is found not to be in normal form then a new trusted
+- * #GVariant is created with the same value as @value.
++ * #GVariant is created with the same value as @value. The non-normal parts of
++ * @value will be replaced with default values which are guaranteed to be in
++ * normal form.
+  *
+  * It makes sense to call this function if you've received #GVariant
+  * data from untrusted sources and you want to ensure your serialized
+-- 
+GitLab
+
+
+From b0ccb1616688290088e49dea2dc0d7fe723136e4 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Mon, 24 Oct 2022 18:43:55 +0100
+Subject: [PATCH 12/18] gvariant: Port g_variant_deep_copy() to count its
+ iterations directly
+
+This is equivalent to what `GVariantIter` does, but it means that
+`g_variant_deep_copy()` is making its own `g_variant_get_child_value()`
+calls.
+
+This will be useful in an upcoming commit, where those child values will
+be inspected a little more deeply.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2121
+---
+ glib/gvariant.c | 7 +++----
+ 1 file changed, 3 insertions(+), 4 deletions(-)
+
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index e92564eb64..82a921a89e 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -5863,14 +5863,13 @@ g_variant_deep_copy (GVariant *value)
+     case G_VARIANT_CLASS_VARIANT:
+       {
+         GVariantBuilder builder;
+-        GVariantIter iter;
+-        GVariant *child;
++        gsize i, n_children;
+ 
+         g_variant_builder_init (&builder, g_variant_get_type (value));
+-        g_variant_iter_init (&iter, value);
+ 
+-        while ((child = g_variant_iter_next_value (&iter)))
++        for (i = 0, n_children = g_variant_n_children (value); i < n_children; i++)
+           {
++            GVariant *child = g_variant_get_child_value (value, i);
+             g_variant_builder_add_value (&builder, g_variant_deep_copy (child));
+             g_variant_unref (child);
+           }
+-- 
+GitLab
+
+
+From 1770e255ae6cc3f0bf5312322432bbc6524a3632 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Tue, 25 Oct 2022 13:03:22 +0100
+Subject: [PATCH 13/18] gvariant: Add internal
+ g_variant_maybe_get_child_value()
+
+This will be used in a following commit.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2540
+---
+ glib/gvariant-core.c | 68 ++++++++++++++++++++++++++++++++++++++++++++
+ glib/gvariant-core.h |  3 ++
+ 2 files changed, 71 insertions(+)
+
+diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
+index e61242f763..3f4ca0e6dc 100644
+--- a/glib/gvariant-core.c
++++ b/glib/gvariant-core.c
+@@ -1204,6 +1204,74 @@ g_variant_get_child_value (GVariant *value,
+   }
+ }
+ 
++/**
++ * g_variant_maybe_get_child_value:
++ * @value: a container #GVariant
++ * @index_: the index of the child to fetch
++ *
++ * Reads a child item out of a container #GVariant instance, if it is in normal
++ * form. If it is not in normal form, return %NULL.
++ *
++ * This function behaves the same as g_variant_get_child_value(), except that it
++ * returns %NULL if the child is not in normal form. g_variant_get_child_value()
++ * would instead return a new default value of the correct type.
++ *
++ * This is intended to be used internally to avoid unnecessary #GVariant
++ * allocations.
++ *
++ * The returned value is never floating.  You should free it with
++ * g_variant_unref() when you're done with it.
++ *
++ * This function is O(1).
++ *
++ * Returns: (transfer full): the child at the specified index
++ *
++ * Since: 2.74
++ */
++GVariant *
++g_variant_maybe_get_child_value (GVariant *value,
++                                 gsize     index_)
++{
++  g_return_val_if_fail (index_ < g_variant_n_children (value), NULL);
++  g_return_val_if_fail (value->depth < G_MAXSIZE, NULL);
++
++  if (~g_atomic_int_get (&value->state) & STATE_SERIALISED)
++    {
++      g_variant_lock (value);
++
++      if (~value->state & STATE_SERIALISED)
++        {
++          GVariant *child;
++
++          child = g_variant_ref (value->contents.tree.children[index_]);
++          g_variant_unlock (value);
++
++          return child;
++        }
++
++      g_variant_unlock (value);
++    }
++
++  {
++    GVariantSerialised serialised = g_variant_to_serialised (value);
++    GVariantSerialised s_child;
++
++    /* get the serializer to extract the serialized data for the child
++     * from the serialized data for the container
++     */
++    s_child = g_variant_serialised_get_child (serialised, index_);
++
++    if (!(value->state & STATE_TRUSTED) && s_child.data == NULL)
++      {
++        g_variant_type_info_unref (s_child.type_info);
++        return NULL;
++      }
++
++    g_variant_type_info_unref (s_child.type_info);
++    return g_variant_get_child_value (value, index_);
++  }
++}
++
+ /**
+  * g_variant_store:
+  * @value: the #GVariant to store
+diff --git a/glib/gvariant-core.h b/glib/gvariant-core.h
+index a1c34739a3..fb5f4bff45 100644
+--- a/glib/gvariant-core.h
++++ b/glib/gvariant-core.h
+@@ -38,4 +38,7 @@ GVariantTypeInfo *      g_variant_get_type_info                         (GVarian
+ 
+ gsize                   g_variant_get_depth                             (GVariant            *value);
+ 
++GVariant *              g_variant_maybe_get_child_value                 (GVariant            *value,
++                                                                         gsize                index_);
++
+ #endif /* __G_VARIANT_CORE_H__ */
+-- 
+GitLab
+
+
+From 82fc15af4c84a2645343c51b18ab3528c51790ab Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Tue, 25 Oct 2022 13:03:45 +0100
+Subject: [PATCH 14/18] gvariant: Cut allocs of default values for children of
+ non-normal arrays
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This improves a slow case in `g_variant_get_normal_form()` where
+allocating many identical default values for the children of a
+variable-sized array which has a malformed offset table would take a lot
+of time.
+
+The fix is to make all child values after the first invalid one be
+references to the default value emitted for the first invalid one,
+rather than identical new `GVariant`s.
+
+In particular, this fixes a case where an attacker could create an array
+of length L of very large tuples of size T each, corrupt the offset table
+so they don’t have to specify the array content, and then induce
+`g_variant_get_normal_form()` into allocating L×T default values from an
+input which is significantly smaller than L×T in length.
+
+A pre-existing workaround for this issue is for code to call
+`g_variant_is_normal_form()` before calling
+`g_variant_get_normal_form()`, and to skip the latter call if the former
+returns false. This commit improves the behaviour in the case that
+`g_variant_get_normal_form()` is called anyway.
+
+This fix changes the time to run the `fuzz_variant_binary` test on the
+testcase from oss-fuzz#19777 from >60s (before being terminated) with
+2.3GB of memory usage and 580k page faults; to 32s, 8.3MB of memory
+usage and 1500 page faults (as measured by `time -v`).
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Fixes: #2540
+oss-fuzz#19777
+---
+ glib/gvariant.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++-
+ 1 file changed, 65 insertions(+), 1 deletion(-)
+
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index 82a921a89e..bb6be363e0 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -5857,7 +5857,6 @@ g_variant_deep_copy (GVariant *value)
+   switch (g_variant_classify (value))
+     {
+     case G_VARIANT_CLASS_MAYBE:
+-    case G_VARIANT_CLASS_ARRAY:
+     case G_VARIANT_CLASS_TUPLE:
+     case G_VARIANT_CLASS_DICT_ENTRY:
+     case G_VARIANT_CLASS_VARIANT:
+@@ -5877,6 +5876,71 @@ g_variant_deep_copy (GVariant *value)
+         return g_variant_builder_end (&builder);
+       }
+ 
++    case G_VARIANT_CLASS_ARRAY:
++      {
++        GVariantBuilder builder;
++        gsize i, n_children;
++        GVariant *first_invalid_child_deep_copy = NULL;
++
++        /* Arrays are in theory treated the same as maybes, tuples, dict entries
++         * and variants, and could be another case in the above block of code.
++         *
++         * However, they have the property that when dealing with non-normal
++         * data (which is the only time g_variant_deep_copy() is currently
++         * called) in a variable-sized array, the code above can easily end up
++         * creating many default child values in order to return an array which
++         * is of the right length and type, but without containing non-normal
++         * data. This can happen if the offset table for the array is malformed.
++         *
++         * In this case, the code above would end up allocating the same default
++         * value for each one of the child indexes beyond the first malformed
++         * entry in the offset table. This can end up being a lot of identical
++         * allocations of default values, particularly if the non-normal array
++         * is crafted maliciously.
++         *
++         * Avoid that problem by returning a new reference to the same default
++         * value for every child after the first invalid one. This results in
++         * returning an equivalent array, in normal form and trusted — but with
++         * significantly fewer memory allocations.
++         *
++         * See https://gitlab.gnome.org/GNOME/glib/-/issues/2540 */
++
++        g_variant_builder_init (&builder, g_variant_get_type (value));
++
++        for (i = 0, n_children = g_variant_n_children (value); i < n_children; i++)
++          {
++            /* Try maybe_get_child_value() first; if it returns NULL, this child
++             * is non-normal. get_child_value() would have constructed and
++             * returned a default value in that case. */
++            GVariant *child = g_variant_maybe_get_child_value (value, i);
++
++            if (child != NULL)
++              {
++                /* Non-normal children may not always be contiguous, as they may
++                 * be non-normal for reasons other than invalid offset table
++                 * entries. As they are all the same type, they will all have
++                 * the same default value though, so keep that around. */
++                g_variant_builder_add_value (&builder, g_variant_deep_copy (child));
++              }
++            else if (child == NULL && first_invalid_child_deep_copy != NULL)
++              {
++                g_variant_builder_add_value (&builder, first_invalid_child_deep_copy);
++              }
++            else if (child == NULL)
++              {
++                child = g_variant_get_child_value (value, i);
++                first_invalid_child_deep_copy = g_variant_ref_sink (g_variant_deep_copy (child));
++                g_variant_builder_add_value (&builder, first_invalid_child_deep_copy);
++              }
++
++            g_clear_pointer (&child, g_variant_unref);
++          }
++
++        g_clear_pointer (&first_invalid_child_deep_copy, g_variant_unref);
++
++        return g_variant_builder_end (&builder);
++      }
++
+     case G_VARIANT_CLASS_BOOLEAN:
+       return g_variant_new_boolean (g_variant_get_boolean (value));
+ 
+-- 
+GitLab
+
+
+From 935f1c200789c76ad5b51b1f403f611e3cc75318 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Tue, 25 Oct 2022 18:03:56 +0100
+Subject: [PATCH 15/18] gvariant: Fix a leak of a GVariantTypeInfo on an error
+ handling path
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+---
+ glib/gvariant-core.c | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
+index 3f4ca0e6dc..75d23f39af 100644
+--- a/glib/gvariant-core.c
++++ b/glib/gvariant-core.c
+@@ -1183,6 +1183,7 @@ g_variant_get_child_value (GVariant *value,
+         G_VARIANT_MAX_RECURSION_DEPTH - value->depth)
+       {
+         g_assert (g_variant_is_of_type (value, G_VARIANT_TYPE_VARIANT));
++        g_variant_type_info_unref (s_child.type_info);
+         return g_variant_new_tuple (NULL, 0);
+       }
+ 
+-- 
+GitLab
+
+
+From f1dfc5d0c5c0486b5fccb2ceddf1db1162c7033c Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Thu, 27 Oct 2022 12:00:04 +0100
+Subject: [PATCH 16/18] gvariant-serialiser: Check offset table entry size is
+ minimal
+
+The entries in an offset table (which is used for variable sized arrays
+and tuples containing variable sized members) are sized so that they can
+address every byte in the overall variant.
+
+The specification requires that for a variant to be in normal form, its
+offset table entries must be the minimum width such that they can
+address every byte in the variant.
+
+That minimality requirement was not checked in
+`g_variant_is_normal_form()`, leading to two different byte arrays being
+interpreted as the normal form of a given variant tree. That kind of
+confusion could potentially be exploited, and is certainly a bug.
+
+Fix it by adding the necessary checks on offset table entry width, and
+unit tests.
+
+Spotted by William Manley.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Fixes: #2794
+---
+ glib/gvariant-serialiser.c |  19 +++-
+ glib/tests/gvariant.c      | 176 +++++++++++++++++++++++++++++++++++++
+ 2 files changed, 194 insertions(+), 1 deletion(-)
+
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index 591522a2e1..25c85b30b1 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -696,6 +696,10 @@ gvs_variable_sized_array_get_frame_offsets (GVariantSerialised value)
+   out.data_size = last_end;
+   out.array = value.data + last_end;
+   out.length = offsets_array_size / out.offset_size;
++
++  if (out.length > 0 && gvs_calculate_total_size (last_end, out.length) != value.size)
++    return out;  /* offset size not minimal */
++
+   out.is_normal = TRUE;
+ 
+   return out;
+@@ -1203,6 +1207,7 @@ gvs_tuple_is_normal (GVariantSerialised value)
+   gsize length;
+   gsize offset;
+   gsize i;
++  gsize offset_table_size;
+ 
+   /* as per the comment in gvs_tuple_get_child() */
+   if G_UNLIKELY (value.data == NULL && value.size != 0)
+@@ -1307,7 +1312,19 @@ gvs_tuple_is_normal (GVariantSerialised value)
+       }
+   }
+ 
+-  return offset_ptr == offset;
++  /* @offset_ptr has been counting backwards from the end of the variant, to
++   * find the beginning of the offset table. @offset has been counting forwards
++   * from the beginning of the variant to find the end of the data. They should
++   * have met in the middle. */
++  if (offset_ptr != offset)
++    return FALSE;
++
++  offset_table_size = value.size - offset_ptr;
++  if (value.size > 0 &&
++      gvs_calculate_total_size (offset, offset_table_size / offset_size) != value.size)
++    return FALSE;  /* offset size not minimal */
++
++  return TRUE;
+ }
+ 
+ /* Variants {{{2
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index 9739993e66..339edc4e04 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -5222,6 +5222,86 @@ test_normal_checking_array_offsets2 (void)
+   g_variant_unref (variant);
+ }
+ 
++/* Test that an otherwise-valid serialised GVariant is considered non-normal if
++ * its offset table entries are too wide.
++ *
++ * See §2.3.6 (Framing Offsets) of the GVariant specification. */
++static void
++test_normal_checking_array_offsets_minimal_sized (void)
++{
++  GVariantBuilder builder;
++  gsize i;
++  GVariant *aay_constructed = NULL;
++  const guint8 *data = NULL;
++  guint8 *data_owned = NULL;
++  GVariant *aay_deserialised = NULL;
++  GVariant *aay_normalised = NULL;
++
++  /* Construct an array of type aay, consisting of 128 elements which are each
++   * an empty array, i.e. `[[] * 128]`. This is chosen because the inner
++   * elements are variable sized (making the outer array variable sized, so it
++   * must have an offset table), but they are also zero-sized when serialised.
++   * So the serialised representation of @aay_constructed consists entirely of
++   * its offset table, which is entirely zeroes.
++   *
++   * The array is chosen to be 128 elements long because that means offset
++   * table entries which are 1 byte long. If the elements in the array were
++   * non-zero-sized (to the extent that the overall array is ≥256 bytes long),
++   * the offset table entries would end up being 2 bytes long. */
++  g_variant_builder_init (&builder, G_VARIANT_TYPE ("aay"));
++
++  for (i = 0; i < 128; i++)
++    g_variant_builder_add_value (&builder, g_variant_new_array (G_VARIANT_TYPE_BYTE, NULL, 0));
++
++  aay_constructed = g_variant_builder_end (&builder);
++
++  /* Verify that the constructed array is in normal form, and its serialised
++   * form is `b'\0' * 128`. */
++  g_assert_true (g_variant_is_normal_form (aay_constructed));
++  g_assert_cmpuint (g_variant_n_children (aay_constructed), ==, 128);
++  g_assert_cmpuint (g_variant_get_size (aay_constructed), ==, 128);
++
++  data = g_variant_get_data (aay_constructed);
++  for (i = 0; i < g_variant_get_size (aay_constructed); i++)
++    g_assert_cmpuint (data[i], ==, 0);
++
++  /* Construct a serialised `aay` GVariant which is `b'\0' * 256`. This has to
++   * be a non-normal form of `[[] * 128]`, with 2-byte-long offset table
++   * entries, because each offset table entry has to be able to reference all of
++   * the byte boundaries in the container. All the entries in the offset table
++   * are zero, so all the elements of the array are zero-sized. */
++  data = data_owned = g_malloc0 (256);
++  aay_deserialised = g_variant_new_from_data (G_VARIANT_TYPE ("aay"),
++                                              data,
++                                              256,
++                                              FALSE,
++                                              g_free,
++                                              g_steal_pointer (&data_owned));
++
++  g_assert_false (g_variant_is_normal_form (aay_deserialised));
++  g_assert_cmpuint (g_variant_n_children (aay_deserialised), ==, 128);
++  g_assert_cmpuint (g_variant_get_size (aay_deserialised), ==, 256);
++
++  data = g_variant_get_data (aay_deserialised);
++  for (i = 0; i < g_variant_get_size (aay_deserialised); i++)
++    g_assert_cmpuint (data[i], ==, 0);
++
++  /* Get its normal form. That should change the serialised size. */
++  aay_normalised = g_variant_get_normal_form (aay_deserialised);
++
++  g_assert_true (g_variant_is_normal_form (aay_normalised));
++  g_assert_cmpuint (g_variant_n_children (aay_normalised), ==, 128);
++  g_assert_cmpuint (g_variant_get_size (aay_normalised), ==, 128);
++
++  data = g_variant_get_data (aay_normalised);
++  for (i = 0; i < g_variant_get_size (aay_normalised); i++)
++    g_assert_cmpuint (data[i], ==, 0);
++
++  g_variant_unref (aay_normalised);
++  g_variant_unref (aay_deserialised);
++  g_variant_unref (aay_constructed);
++}
++
+ /* Test that a tuple with invalidly large values in its offset table is
+  * normalised successfully without looping infinitely. */
+ static void
+@@ -5416,6 +5496,98 @@ test_normal_checking_tuple_offsets4 (void)
+   g_variant_unref (variant);
+ }
+ 
++/* Test that an otherwise-valid serialised GVariant is considered non-normal if
++ * its offset table entries are too wide.
++ *
++ * See §2.3.6 (Framing Offsets) of the GVariant specification. */
++static void
++test_normal_checking_tuple_offsets_minimal_sized (void)
++{
++  GString *type_string = NULL;
++  GVariantBuilder builder;
++  gsize i;
++  GVariant *ray_constructed = NULL;
++  const guint8 *data = NULL;
++  guint8 *data_owned = NULL;
++  GVariant *ray_deserialised = NULL;
++  GVariant *ray_normalised = NULL;
++
++  /* Construct a tuple of type (ay…ay), consisting of 129 members which are each
++   * an empty array, i.e. `([] * 129)`. This is chosen because the inner
++   * members are variable sized, so the outer tuple must have an offset table,
++   * but they are also zero-sized when serialised. So the serialised
++   * representation of @ray_constructed consists entirely of its offset table,
++   * which is entirely zeroes.
++   *
++   * The tuple is chosen to be 129 members long because that means it has 128
++   * offset table entries which are 1 byte long each. If the members in the
++   * tuple were non-zero-sized (to the extent that the overall tuple is ≥256
++   * bytes long), the offset table entries would end up being 2 bytes long.
++   *
++   * 129 members are used unlike 128 array elements in
++   * test_normal_checking_array_offsets_minimal_sized(), because the last member
++   * in a tuple never needs an offset table entry. */
++  type_string = g_string_new ("");
++  g_string_append_c (type_string, '(');
++  for (i = 0; i < 129; i++)
++    g_string_append (type_string, "ay");
++  g_string_append_c (type_string, ')');
++
++  g_variant_builder_init (&builder, G_VARIANT_TYPE (type_string->str));
++
++  for (i = 0; i < 129; i++)
++    g_variant_builder_add_value (&builder, g_variant_new_array (G_VARIANT_TYPE_BYTE, NULL, 0));
++
++  ray_constructed = g_variant_builder_end (&builder);
++
++  /* Verify that the constructed tuple is in normal form, and its serialised
++   * form is `b'\0' * 128`. */
++  g_assert_true (g_variant_is_normal_form (ray_constructed));
++  g_assert_cmpuint (g_variant_n_children (ray_constructed), ==, 129);
++  g_assert_cmpuint (g_variant_get_size (ray_constructed), ==, 128);
++
++  data = g_variant_get_data (ray_constructed);
++  for (i = 0; i < g_variant_get_size (ray_constructed); i++)
++    g_assert_cmpuint (data[i], ==, 0);
++
++  /* Construct a serialised `(ay…ay)` GVariant which is `b'\0' * 256`. This has
++   * to be a non-normal form of `([] * 129)`, with 2-byte-long offset table
++   * entries, because each offset table entry has to be able to reference all of
++   * the byte boundaries in the container. All the entries in the offset table
++   * are zero, so all the members of the tuple are zero-sized. */
++  data = data_owned = g_malloc0 (256);
++  ray_deserialised = g_variant_new_from_data (G_VARIANT_TYPE (type_string->str),
++                                              data,
++                                              256,
++                                              FALSE,
++                                              g_free,
++                                              g_steal_pointer (&data_owned));
++
++  g_assert_false (g_variant_is_normal_form (ray_deserialised));
++  g_assert_cmpuint (g_variant_n_children (ray_deserialised), ==, 129);
++  g_assert_cmpuint (g_variant_get_size (ray_deserialised), ==, 256);
++
++  data = g_variant_get_data (ray_deserialised);
++  for (i = 0; i < g_variant_get_size (ray_deserialised); i++)
++    g_assert_cmpuint (data[i], ==, 0);
++
++  /* Get its normal form. That should change the serialised size. */
++  ray_normalised = g_variant_get_normal_form (ray_deserialised);
++
++  g_assert_true (g_variant_is_normal_form (ray_normalised));
++  g_assert_cmpuint (g_variant_n_children (ray_normalised), ==, 129);
++  g_assert_cmpuint (g_variant_get_size (ray_normalised), ==, 128);
++
++  data = g_variant_get_data (ray_normalised);
++  for (i = 0; i < g_variant_get_size (ray_normalised); i++)
++    g_assert_cmpuint (data[i], ==, 0);
++
++  g_variant_unref (ray_normalised);
++  g_variant_unref (ray_deserialised);
++  g_variant_unref (ray_constructed);
++  g_string_free (type_string, TRUE);
++}
++
+ /* Test that an empty object path is normalised successfully to the base object
+  * path, ‘/’. */
+ static void
+@@ -5564,6 +5736,8 @@ main (int argc, char **argv)
+                    test_normal_checking_array_offsets);
+   g_test_add_func ("/gvariant/normal-checking/array-offsets2",
+                    test_normal_checking_array_offsets2);
++  g_test_add_func ("/gvariant/normal-checking/array-offsets/minimal-sized",
++                   test_normal_checking_array_offsets_minimal_sized);
+   g_test_add_func ("/gvariant/normal-checking/tuple-offsets",
+                    test_normal_checking_tuple_offsets);
+   g_test_add_func ("/gvariant/normal-checking/tuple-offsets2",
+@@ -5572,6 +5746,8 @@ main (int argc, char **argv)
+                    test_normal_checking_tuple_offsets3);
+   g_test_add_func ("/gvariant/normal-checking/tuple-offsets4",
+                    test_normal_checking_tuple_offsets4);
++  g_test_add_func ("/gvariant/normal-checking/tuple-offsets/minimal-sized",
++                   test_normal_checking_tuple_offsets_minimal_sized);
+   g_test_add_func ("/gvariant/normal-checking/empty-object-path",
+                    test_normal_checking_empty_object_path);
+ 
+-- 
+GitLab
+
+
+From 781f05a22ef11d8a2177b4e9078978decec36dd0 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Thu, 27 Oct 2022 16:13:54 +0100
+Subject: [PATCH 17/18] gvariant: Fix g_variant_byteswap() returning non-normal
+ data sometimes
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+If `g_variant_byteswap()` was called on a non-normal variant of a type
+which doesn’t need byteswapping, it would return a non-normal output.
+
+That contradicts the documentation, which says that the return value is
+always in normal form.
+
+Fix the code so it matches the documentation.
+
+Includes a unit test.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2797
+---
+ glib/gvariant.c       |  8 +++++---
+ glib/tests/gvariant.c | 24 ++++++++++++++++++++++++
+ 2 files changed, 29 insertions(+), 3 deletions(-)
+
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index bb6be363e0..b3495d5cab 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -6083,14 +6083,16 @@ g_variant_byteswap (GVariant *value)
+       g_variant_serialised_byteswap (serialised);
+ 
+       bytes = g_bytes_new_take (serialised.data, serialised.size);
+-      new = g_variant_new_from_bytes (g_variant_get_type (value), bytes, TRUE);
++      new = g_variant_ref_sink (g_variant_new_from_bytes (g_variant_get_type (value), bytes, TRUE));
+       g_bytes_unref (bytes);
+     }
+   else
+     /* contains no multi-byte data */
+-    new = value;
++    new = g_variant_get_normal_form (value);
+ 
+-  return g_variant_ref_sink (new);
++  g_assert (g_variant_is_trusted (new));
++
++  return g_steal_pointer (&new);
+ }
+ 
+ /**
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index 339edc4e04..bea16b5e58 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -3826,6 +3826,29 @@ test_gv_byteswap (void)
+   g_free (string);
+ }
+ 
++static void
++test_gv_byteswap_non_normal_non_aligned (void)
++{
++  const guint8 data[] = { 0x02 };
++  GVariant *v = NULL;
++  GVariant *v_byteswapped = NULL;
++
++  g_test_summary ("Test that calling g_variant_byteswap() on a variant which "
++                  "is in non-normal form and doesn’t need byteswapping returns "
++                  "the same variant in normal form.");
++
++  v = g_variant_new_from_data (G_VARIANT_TYPE_BOOLEAN, data, sizeof (data), FALSE, NULL, NULL);
++  g_assert_false (g_variant_is_normal_form (v));
++
++  v_byteswapped = g_variant_byteswap (v);
++  g_assert_true (g_variant_is_normal_form (v_byteswapped));
++
++  g_assert_cmpvariant (v, v_byteswapped);
++
++  g_variant_unref (v);
++  g_variant_unref (v_byteswapped);
++}
++
+ static void
+ test_parser (void)
+ {
+@@ -5699,6 +5722,7 @@ main (int argc, char **argv)
+   g_test_add_func ("/gvariant/builder-memory", test_builder_memory);
+   g_test_add_func ("/gvariant/hashing", test_hashing);
+   g_test_add_func ("/gvariant/byteswap", test_gv_byteswap);
++  g_test_add_func ("/gvariant/byteswap/non-normal-non-aligned", test_gv_byteswap_non_normal_non_aligned);
+   g_test_add_func ("/gvariant/parser", test_parses);
+   g_test_add_func ("/gvariant/parser/integer-bounds", test_parser_integer_bounds);
+   g_test_add_func ("/gvariant/parser/recursion", test_parser_recursion);
+-- 
+GitLab
+
+
+From 7d7efce1d9c379fdd7d2ff58caea88f8806fdd2e Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Thu, 27 Oct 2022 22:53:13 +0100
+Subject: [PATCH 18/18] gvariant: Allow g_variant_byteswap() to operate on
+ tree-form variants
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This avoids needing to always serialise a variant before byteswapping it.
+With variants in non-normal forms, serialisation can result in a large
+increase in size of the variant, and a lot of allocations for leaf
+`GVariant`s. This can lead to a denial of service attack.
+
+Avoid that by changing byteswapping so that it happens on the tree form
+of the variant if the input is in non-normal form. If the input is in
+normal form (either serialised or in tree form), continue using the
+existing code as byteswapping an already-serialised normal variant is
+about 3× faster than byteswapping on the equivalent tree form.
+
+The existing unit tests cover byteswapping well, but need some
+adaptation so that they operate on tree form variants too.
+
+I considered dropping the serialised byteswapping code and doing all
+byteswapping on tree-form variants, as that would make maintenance
+simpler (avoiding having two parallel implementations of byteswapping).
+However, most inputs to `g_variant_byteswap()` are likely to be
+serialised variants (coming from a byte array of input from some foreign
+source) and most of them are going to be in normal form (as corruption
+and malicious action are rare). So getting rid of the serialised
+byteswapping code would impose quite a performance penalty on the common
+case.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Fixes: #2797
+---
+ glib/gvariant.c       | 87 ++++++++++++++++++++++++++++++++-----------
+ glib/tests/gvariant.c | 57 ++++++++++++++++++++++++----
+ 2 files changed, 115 insertions(+), 29 deletions(-)
+
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index b3495d5cab..95904bd382 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -5852,7 +5852,8 @@ g_variant_iter_loop (GVariantIter *iter,
+ 
+ /* Serialized data {{{1 */
+ static GVariant *
+-g_variant_deep_copy (GVariant *value)
++g_variant_deep_copy (GVariant *value,
++                     gboolean  byteswap)
+ {
+   switch (g_variant_classify (value))
+     {
+@@ -5869,7 +5870,7 @@ g_variant_deep_copy (GVariant *value)
+         for (i = 0, n_children = g_variant_n_children (value); i < n_children; i++)
+           {
+             GVariant *child = g_variant_get_child_value (value, i);
+-            g_variant_builder_add_value (&builder, g_variant_deep_copy (child));
++            g_variant_builder_add_value (&builder, g_variant_deep_copy (child, byteswap));
+             g_variant_unref (child);
+           }
+ 
+@@ -5920,7 +5921,7 @@ g_variant_deep_copy (GVariant *value)
+                  * be non-normal for reasons other than invalid offset table
+                  * entries. As they are all the same type, they will all have
+                  * the same default value though, so keep that around. */
+-                g_variant_builder_add_value (&builder, g_variant_deep_copy (child));
++                g_variant_builder_add_value (&builder, g_variant_deep_copy (child, byteswap));
+               }
+             else if (child == NULL && first_invalid_child_deep_copy != NULL)
+               {
+@@ -5929,7 +5930,7 @@ g_variant_deep_copy (GVariant *value)
+             else if (child == NULL)
+               {
+                 child = g_variant_get_child_value (value, i);
+-                first_invalid_child_deep_copy = g_variant_ref_sink (g_variant_deep_copy (child));
++                first_invalid_child_deep_copy = g_variant_ref_sink (g_variant_deep_copy (child, byteswap));
+                 g_variant_builder_add_value (&builder, first_invalid_child_deep_copy);
+               }
+ 
+@@ -5948,28 +5949,63 @@ g_variant_deep_copy (GVariant *value)
+       return g_variant_new_byte (g_variant_get_byte (value));
+ 
+     case G_VARIANT_CLASS_INT16:
+-      return g_variant_new_int16 (g_variant_get_int16 (value));
++      if (byteswap)
++        return g_variant_new_int16 (GUINT16_SWAP_LE_BE (g_variant_get_int16 (value)));
++      else
++        return g_variant_new_int16 (g_variant_get_int16 (value));
+ 
+     case G_VARIANT_CLASS_UINT16:
+-      return g_variant_new_uint16 (g_variant_get_uint16 (value));
++      if (byteswap)
++        return g_variant_new_uint16 (GUINT16_SWAP_LE_BE (g_variant_get_uint16 (value)));
++      else
++        return g_variant_new_uint16 (g_variant_get_uint16 (value));
+ 
+     case G_VARIANT_CLASS_INT32:
+-      return g_variant_new_int32 (g_variant_get_int32 (value));
++      if (byteswap)
++        return g_variant_new_int32 (GUINT32_SWAP_LE_BE (g_variant_get_int32 (value)));
++      else
++        return g_variant_new_int32 (g_variant_get_int32 (value));
+ 
+     case G_VARIANT_CLASS_UINT32:
+-      return g_variant_new_uint32 (g_variant_get_uint32 (value));
++      if (byteswap)
++        return g_variant_new_uint32 (GUINT32_SWAP_LE_BE (g_variant_get_uint32 (value)));
++      else
++        return g_variant_new_uint32 (g_variant_get_uint32 (value));
+ 
+     case G_VARIANT_CLASS_INT64:
+-      return g_variant_new_int64 (g_variant_get_int64 (value));
++      if (byteswap)
++        return g_variant_new_int64 (GUINT64_SWAP_LE_BE (g_variant_get_int64 (value)));
++      else
++        return g_variant_new_int64 (g_variant_get_int64 (value));
+ 
+     case G_VARIANT_CLASS_UINT64:
+-      return g_variant_new_uint64 (g_variant_get_uint64 (value));
++      if (byteswap)
++        return g_variant_new_uint64 (GUINT64_SWAP_LE_BE (g_variant_get_uint64 (value)));
++      else
++        return g_variant_new_uint64 (g_variant_get_uint64 (value));
+ 
+     case G_VARIANT_CLASS_HANDLE:
+-      return g_variant_new_handle (g_variant_get_handle (value));
++      if (byteswap)
++        return g_variant_new_handle (GUINT32_SWAP_LE_BE (g_variant_get_handle (value)));
++      else
++        return g_variant_new_handle (g_variant_get_handle (value));
+ 
+     case G_VARIANT_CLASS_DOUBLE:
+-      return g_variant_new_double (g_variant_get_double (value));
++      if (byteswap)
++        {
++          /* We have to convert the double to a uint64 here using a union,
++           * because a cast will round it numerically. */
++          union
++            {
++              guint64 u64;
++              gdouble dbl;
++            } u1, u2;
++          u1.dbl = g_variant_get_double (value);
++          u2.u64 = GUINT64_SWAP_LE_BE (u1.u64);
++          return g_variant_new_double (u2.dbl);
++        }
++      else
++        return g_variant_new_double (g_variant_get_double (value));
+ 
+     case G_VARIANT_CLASS_STRING:
+       return g_variant_new_string (g_variant_get_string (value, NULL));
+@@ -6026,7 +6062,7 @@ g_variant_get_normal_form (GVariant *value)
+   if (g_variant_is_normal_form (value))
+     return g_variant_ref (value);
+ 
+-  trusted = g_variant_deep_copy (value);
++  trusted = g_variant_deep_copy (value, FALSE);
+   g_assert (g_variant_is_trusted (trusted));
+ 
+   return g_variant_ref_sink (trusted);
+@@ -6046,6 +6082,11 @@ g_variant_get_normal_form (GVariant *value)
+  * contain multi-byte numeric data.  That include strings, booleans,
+  * bytes and containers containing only these things (recursively).
+  *
++ * While this function can safely handle untrusted, non-normal data, it is
++ * recommended to check whether the input is in normal form beforehand, using
++ * g_variant_is_normal_form(), and to reject non-normal inputs if your
++ * application can be strict about what inputs it rejects.
++ *
+  * The returned value is always in normal form and is marked as trusted.
+  *
+  * Returns: (transfer full): the byteswapped form of @value
+@@ -6063,22 +6104,21 @@ g_variant_byteswap (GVariant *value)
+ 
+   g_variant_type_info_query (type_info, &alignment, NULL);
+ 
+-  if (alignment)
+-    /* (potentially) contains multi-byte numeric data */
++  if (alignment && g_variant_is_normal_form (value))
+     {
++      /* (potentially) contains multi-byte numeric data, but is also already in
++       * normal form so we can use a faster byteswapping codepath on the
++       * serialised data */
+       GVariantSerialised serialised = { 0, };
+-      GVariant *trusted;
+       GBytes *bytes;
+ 
+-      trusted = g_variant_get_normal_form (value);
+-      serialised.type_info = g_variant_get_type_info (trusted);
+-      serialised.size = g_variant_get_size (trusted);
++      serialised.type_info = g_variant_get_type_info (value);
++      serialised.size = g_variant_get_size (value);
+       serialised.data = g_malloc (serialised.size);
+-      serialised.depth = g_variant_get_depth (trusted);
++      serialised.depth = g_variant_get_depth (value);
+       serialised.ordered_offsets_up_to = G_MAXSIZE;  /* operating on the normal form */
+       serialised.checked_offsets_up_to = G_MAXSIZE;
+-      g_variant_store (trusted, serialised.data);
+-      g_variant_unref (trusted);
++      g_variant_store (value, serialised.data);
+ 
+       g_variant_serialised_byteswap (serialised);
+ 
+@@ -6086,6 +6126,9 @@ g_variant_byteswap (GVariant *value)
+       new = g_variant_ref_sink (g_variant_new_from_bytes (g_variant_get_type (value), bytes, TRUE));
+       g_bytes_unref (bytes);
+     }
++  else if (alignment)
++    /* (potentially) contains multi-byte numeric data */
++    new = g_variant_ref_sink (g_variant_deep_copy (value, TRUE));
+   else
+     /* contains no multi-byte data */
+     new = g_variant_get_normal_form (value);
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index bea16b5e58..ba837af48d 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -2288,24 +2288,67 @@ serialise_tree (TreeInstance       *tree,
+ static void
+ test_byteswap (void)
+ {
+-  GVariantSerialised one = { 0, }, two = { 0, };
++  GVariantSerialised one = { 0, }, two = { 0, }, three = { 0, };
+   TreeInstance *tree;
+-
++  GVariant *one_variant = NULL;
++  GVariant *two_variant = NULL;
++  GVariant *two_byteswapped = NULL;
++  GVariant *three_variant = NULL;
++  GVariant *three_byteswapped = NULL;
++  guint8 *three_data_copy = NULL;
++  gsize three_size_copy = 0;
++
++  /* Write a tree out twice, once normally and once byteswapped. */
+   tree = tree_instance_new (NULL, 3);
+   serialise_tree (tree, &one);
+ 
++  one_variant = g_variant_new_from_data (G_VARIANT_TYPE (g_variant_type_info_get_type_string (one.type_info)),
++                                         one.data, one.size, FALSE, NULL, NULL);
++
+   i_am_writing_byteswapped = TRUE;
+   serialise_tree (tree, &two);
++  serialise_tree (tree, &three);
+   i_am_writing_byteswapped = FALSE;
+ 
+-  g_variant_serialised_byteswap (two);
+-
+-  g_assert_cmpmem (one.data, one.size, two.data, two.size);
+-  g_assert_cmpuint (one.depth, ==, two.depth);
+-
++  /* Swap the first byteswapped one back using the function we want to test. */
++  two_variant = g_variant_new_from_data (G_VARIANT_TYPE (g_variant_type_info_get_type_string (two.type_info)),
++                                         two.data, two.size, FALSE, NULL, NULL);
++  two_byteswapped = g_variant_byteswap (two_variant);
++
++  /* Make the second byteswapped one non-normal (hopefully), and then byteswap
++   * it back using the function we want to test in its non-normal mode.
++   * This might not work because it’s not necessarily possible to make an
++   * arbitrary random variant non-normal. Adding a single zero byte to the end
++   * often makes something non-normal but still readable. */
++  three_size_copy = three.size + 1;
++  three_data_copy = g_malloc (three_size_copy);
++  memcpy (three_data_copy, three.data, three.size);
++  three_data_copy[three.size] = '\0';
++
++  three_variant = g_variant_new_from_data (G_VARIANT_TYPE (g_variant_type_info_get_type_string (three.type_info)),
++                                           three_data_copy, three_size_copy, FALSE, NULL, NULL);
++  three_byteswapped = g_variant_byteswap (three_variant);
++
++  /* Check they’re the same. We can always compare @one_variant and
++   * @two_byteswapped. We can only compare @two_byteswapped and
++   * @three_byteswapped if @two_variant and @three_variant are equal: in that
++   * case, the corruption to @three_variant was enough to make it non-normal but
++   * not enough to change its value. */
++  g_assert_cmpvariant (one_variant, two_byteswapped);
++
++  if (g_variant_equal (two_variant, three_variant))
++    g_assert_cmpvariant (two_byteswapped, three_byteswapped);
++
++  g_variant_unref (three_byteswapped);
++  g_variant_unref (three_variant);
++  g_variant_unref (two_byteswapped);
++  g_variant_unref (two_variant);
++  g_variant_unref (one_variant);
+   tree_instance_free (tree);
+   g_free (one.data);
+   g_free (two.data);
++  g_free (three.data);
++  g_free (three_data_copy);
+ }
+ 
+ static void
+-- 
+GitLab
+
+
diff --git a/dev-libs/glib/glib-2.68.3-r2.ebuild b/dev-libs/glib/glib-2.68.3-r2.ebuild
index 03f963d..958d58b 100644
--- a/dev-libs/glib/glib-2.68.3-r2.ebuild
+++ b/dev-libs/glib/glib-2.68.3-r2.ebuild
@@ -73,6 +73,8 @@
 	"${FILESDIR}"/${PN}-2.64.1-mark-gdbus-server-auth-test-flaky.patch
 	"${FILESDIR}/glib-2.66.7-CHROMIUM-gdbus-system-bus-address.patch"
 	"${FILESDIR}"/${PN}-2.68.3-glibc-2.34-close_range.patch
+	"${FILESDIR}"/glib-2.74.1-normal-form-handling-gvariant.patch
+	"${FILESDIR}"/glib-2.74.1-normal-form-handling-gvariant-patch-fixes.patch
 )
 
 pkg_setup() {
diff --git a/dev-util/glib-utils/files/glib-2.74.1-normal-form-handling-gvariant-patch-fixes.patch b/dev-util/glib-utils/files/glib-2.74.1-normal-form-handling-gvariant-patch-fixes.patch
new file mode 100644
index 0000000..612d2ab
--- /dev/null
+++ b/dev-util/glib-utils/files/glib-2.74.1-normal-form-handling-gvariant-patch-fixes.patch
@@ -0,0 +1,200 @@
+From bf008669f26f70426ca30ee8cdcbd48e41a74718 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Thu, 15 Dec 2022 13:00:39 +0000
+Subject: [PATCH 1/2] =?UTF-8?q?gvariant:=20Check=20offset=20table=20doesn?=
+ =?UTF-8?q?=E2=80=99t=20fall=20outside=20variant=20bounds?=
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+When dereferencing the first entry in the offset table for a tuple,
+check that it doesn’t fall outside the bounds of the variant first.
+
+This prevents an out-of-bounds read from some non-normal tuples.
+
+This bug was introduced in commit 73d0aa81c2575a5c9ae77d.
+
+Includes a unit test, although the test will likely only catch the
+original bug if run with asan enabled.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Fixes: #2840
+oss-fuzz#54302
+---
+ glib/gvariant-serialiser.c | 12 ++++++--
+ glib/tests/gvariant.c      | 63 ++++++++++++++++++++++++++++++++++++++
+ 2 files changed, 72 insertions(+), 3 deletions(-)
+
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index e9b0eab2b4..af863cc526 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -984,7 +984,8 @@ gvs_tuple_get_member_bounds (GVariantSerialised  value,
+ 
+   member_info = g_variant_type_info_member_info (value.type_info, index_);
+ 
+-  if (member_info->i + 1)
++  if (member_info->i + 1 &&
++      offset_size * (member_info->i + 1) <= value.size)
+     member_start = gvs_read_unaligned_le (value.data + value.size -
+                                           offset_size * (member_info->i + 1),
+                                           offset_size);
+@@ -995,7 +996,8 @@ gvs_tuple_get_member_bounds (GVariantSerialised  value,
+   member_start &= member_info->b;
+   member_start |= member_info->c;
+ 
+-  if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_LAST)
++  if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_LAST &&
++      offset_size * (member_info->i + 1) <= value.size)
+     member_end = value.size - offset_size * (member_info->i + 1);
+ 
+   else if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_FIXED)
+@@ -1006,11 +1008,15 @@ gvs_tuple_get_member_bounds (GVariantSerialised  value,
+       member_end = member_start + fixed_size;
+     }
+ 
+-  else /* G_VARIANT_MEMBER_ENDING_OFFSET */
++  else if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_OFFSET &&
++           offset_size * (member_info->i + 2) <= value.size)
+     member_end = gvs_read_unaligned_le (value.data + value.size -
+                                         offset_size * (member_info->i + 2),
+                                         offset_size);
+ 
++  else  /* invalid */
++    member_end = G_MAXSIZE;
++
+   if (out_member_start != NULL)
+     *out_member_start = member_start;
+   if (out_member_end != NULL)
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index ba837af48d..e4a2518aa6 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -5562,6 +5562,67 @@ test_normal_checking_tuple_offsets4 (void)
+   g_variant_unref (variant);
+ }
+ 
++/* This is a regression test that dereferencing the first element in the offset
++ * table doesn’t dereference memory before the start of the GVariant. The first
++ * element in the offset table gives the offset of the final member in the
++ * tuple (the offset table is stored in reverse), and the position of this final
++ * member is needed to check that none of the tuple members overlap with the
++ * offset table
++ *
++ * See https://gitlab.gnome.org/GNOME/glib/-/issues/2840 */
++static void
++test_normal_checking_tuple_offsets5 (void)
++{
++  /* A tuple of type (sss) in normal form would have an offset table with two
++   * entries:
++   *  - The first entry (lowest index in the table) gives the offset of the
++   *    third `s` in the tuple, as the offset table is reversed compared to the
++   *    tuple members.
++   *  - The second entry (highest index in the table) gives the offset of the
++   *    second `s` in the tuple.
++   *  - The offset of the first `s` in the tuple is always 0.
++   *
++   * See §2.5.4 (Structures) of the GVariant specification for details, noting
++   * that the table is only layed out this way because all three members of the
++   * tuple have non-fixed sizes.
++   *
++   * It’s not clear whether the 0xaa data of this variant is part of the strings
++   * in the tuple, or part of the offset table. It doesn’t really matter. This
++   * is a regression test to check that the code to validate the offset table
++   * doesn’t unconditionally try to access the first entry in the offset table
++   * by subtracting the table size from the end of the GVariant data.
++   *
++   * In this non-normal case, that would result in an address off the start of
++   * the GVariant data, and an out-of-bounds read, because the GVariant is one
++   * byte long, but the offset table is calculated as two bytes long (with 1B
++   * sized entries) from the tuple’s type.
++   */
++  const GVariantType *data_type = G_VARIANT_TYPE ("(sss)");
++  const guint8 data[] = { 0xaa };
++  gsize size = sizeof (data);
++  GVariant *variant = NULL;
++  GVariant *normal_variant = NULL;
++  GVariant *expected = NULL;
++
++  g_test_bug ("https://gitlab.gnome.org/GNOME/glib/-/issues/2840");
++
++  variant = g_variant_new_from_data (data_type, data, size, FALSE, NULL, NULL);
++  g_assert_nonnull (variant);
++
++  g_assert_false (g_variant_is_normal_form (variant));
++
++  normal_variant = g_variant_get_normal_form (variant);
++  g_assert_nonnull (normal_variant);
++
++  expected = g_variant_new_parsed ("('', '', '')");
++  g_assert_cmpvariant (expected, variant);
++  g_assert_cmpvariant (expected, normal_variant);
++
++  g_variant_unref (expected);
++  g_variant_unref (normal_variant);
++  g_variant_unref (variant);
++}
++
+ /* Test that an otherwise-valid serialised GVariant is considered non-normal if
+  * its offset table entries are too wide.
+  *
+@@ -5813,6 +5874,8 @@ main (int argc, char **argv)
+                    test_normal_checking_tuple_offsets3);
+   g_test_add_func ("/gvariant/normal-checking/tuple-offsets4",
+                    test_normal_checking_tuple_offsets4);
++  g_test_add_func ("/gvariant/normal-checking/tuple-offsets5",
++                   test_normal_checking_tuple_offsets5);
+   g_test_add_func ("/gvariant/normal-checking/tuple-offsets/minimal-sized",
+                    test_normal_checking_tuple_offsets_minimal_sized);
+   g_test_add_func ("/gvariant/normal-checking/empty-object-path",
+-- 
+GitLab
+
+
+From 4d0bed8c4690f7a2692474ef6a570bd99ef45ef1 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Thu, 15 Dec 2022 16:49:28 +0000
+Subject: [PATCH 2/2] gvariant: Propagate trust when getting a child of a
+ serialised variant
+
+If a variant is trusted, that means all its children are trusted, so
+ensure that their checked offsets are set as such.
+
+This allows a lot of the offset table checks to be avoided when getting
+children from trusted serialised tuples, which speeds things up.
+
+No unit test is included because this is just a performance fix. If
+there are other slownesses, or regressions, in serialised `GVariant`
+performance, the fuzzing setup will catch them like it did this one.
+
+This change does reduce the time to run the oss-fuzz reproducer from 80s
+to about 0.7s on my machine.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Fixes: #2841
+oss-fuzz#54314
+---
+ glib/gvariant-core.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
+index 75d23f39af..57bbf88cc9 100644
+--- a/glib/gvariant-core.c
++++ b/glib/gvariant-core.c
+@@ -1198,8 +1198,8 @@ g_variant_get_child_value (GVariant *value,
+     child->contents.serialised.bytes =
+       g_bytes_ref (value->contents.serialised.bytes);
+     child->contents.serialised.data = s_child.data;
+-    child->contents.serialised.ordered_offsets_up_to = s_child.ordered_offsets_up_to;
+-    child->contents.serialised.checked_offsets_up_to = s_child.checked_offsets_up_to;
++    child->contents.serialised.ordered_offsets_up_to = (value->state & STATE_TRUSTED) ? G_MAXSIZE : s_child.ordered_offsets_up_to;
++    child->contents.serialised.checked_offsets_up_to = (value->state & STATE_TRUSTED) ? G_MAXSIZE : s_child.checked_offsets_up_to;
+ 
+     return child;
+   }
+-- 
+GitLab
+
+
diff --git a/dev-util/glib-utils/files/glib-2.74.1-normal-form-handling-gvariant.patch b/dev-util/glib-utils/files/glib-2.74.1-normal-form-handling-gvariant.patch
new file mode 100644
index 0000000..1d75331
--- /dev/null
+++ b/dev-util/glib-utils/files/glib-2.74.1-normal-form-handling-gvariant.patch
@@ -0,0 +1,2975 @@
+From 590f7a6b76b5a3695aa562c9c3ab244433b6624b Mon Sep 17 00:00:00 2001
+From: William Manley <will@stb-tester.com>
+Date: Tue, 23 Jun 2020 22:59:58 +0100
+Subject: [PATCH 01/18] gvariant-core: Consolidate construction of
+ `GVariantSerialised`
+
+So I only need to change it in one place.
+
+This introduces no functional changes.
+
+Helps: #2121
+---
+ glib/gvariant-core.c | 49 ++++++++++++++++++++++----------------------
+ 1 file changed, 25 insertions(+), 24 deletions(-)
+
+diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
+index ad0bab5b62..70c712ddc0 100644
+--- a/glib/gvariant-core.c
++++ b/glib/gvariant-core.c
+@@ -351,6 +351,27 @@ g_variant_ensure_size (GVariant *value)
+     }
+ }
+ 
++/* < private >
++ * g_variant_to_serialised:
++ * @value: a #GVariant
++ *
++ * Gets a GVariantSerialised for a GVariant in state STATE_SERIALISED.
++ */
++inline static GVariantSerialised
++g_variant_to_serialised (GVariant *value)
++{
++  g_assert (value->state & STATE_SERIALISED);
++  {
++    GVariantSerialised serialised = {
++      value->type_info,
++      (gpointer) value->contents.serialised.data,
++      value->size,
++      value->depth,
++    };
++    return serialised;
++  }
++}
++
+ /* < private >
+  * g_variant_serialise:
+  * @value: a #GVariant
+@@ -1009,16 +1030,8 @@ g_variant_n_children (GVariant *value)
+   g_variant_lock (value);
+ 
+   if (value->state & STATE_SERIALISED)
+-    {
+-      GVariantSerialised serialised = {
+-        value->type_info,
+-        (gpointer) value->contents.serialised.data,
+-        value->size,
+-        value->depth,
+-      };
+-
+-      n_children = g_variant_serialised_n_children (serialised);
+-    }
++    n_children = g_variant_serialised_n_children (
++        g_variant_to_serialised (value));
+   else
+     n_children = value->contents.tree.n_children;
+ 
+@@ -1085,12 +1098,7 @@ g_variant_get_child_value (GVariant *value,
+     }
+ 
+   {
+-    GVariantSerialised serialised = {
+-      value->type_info,
+-      (gpointer) value->contents.serialised.data,
+-      value->size,
+-      value->depth,
+-    };
++    GVariantSerialised serialised = g_variant_to_serialised (value);
+     GVariantSerialised s_child;
+     GVariant *child;
+ 
+@@ -1203,14 +1211,7 @@ g_variant_is_normal_form (GVariant *value)
+ 
+   if (value->state & STATE_SERIALISED)
+     {
+-      GVariantSerialised serialised = {
+-        value->type_info,
+-        (gpointer) value->contents.serialised.data,
+-        value->size,
+-        value->depth
+-      };
+-
+-      if (g_variant_serialised_is_normal (serialised))
++      if (g_variant_serialised_is_normal (g_variant_to_serialised (value)))
+         value->state |= STATE_TRUSTED;
+     }
+   else
+-- 
+GitLab
+
+
+From f8f5d8eefa06008aa8fe684069193dc3b1ae1b58 Mon Sep 17 00:00:00 2001
+From: William Manley <will@stb-tester.com>
+Date: Thu, 25 Jun 2020 17:08:21 +0100
+Subject: [PATCH 02/18] gvariant-serialiser: Factor out functions for dealing
+ with framing offsets
+
+This introduces no functional changes.
+
+Helps: #2121
+---
+ glib/gvariant-serialiser.c | 108 +++++++++++++++++++------------------
+ 1 file changed, 57 insertions(+), 51 deletions(-)
+
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index 3af68b79b2..09492e4526 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -635,30 +635,62 @@ gvs_calculate_total_size (gsize body_size,
+   return body_size + 8 * offsets;
+ }
+ 
++struct Offsets
++{
++  gsize     data_size;
++
++  guchar   *array;
++  gsize     length;
++  guint     offset_size;
++
++  gboolean  is_normal;
++};
++
+ static gsize
+-gvs_variable_sized_array_n_children (GVariantSerialised value)
++gvs_offsets_get_offset_n (struct Offsets *offsets,
++                          gsize           n)
++{
++  return gvs_read_unaligned_le (
++      offsets->array + (offsets->offset_size * n), offsets->offset_size);
++}
++
++static struct Offsets
++gvs_variable_sized_array_get_frame_offsets (GVariantSerialised value)
+ {
++  struct Offsets out = { 0, };
+   gsize offsets_array_size;
+-  gsize offset_size;
+   gsize last_end;
+ 
+   if (value.size == 0)
+-    return 0;
+-
+-  offset_size = gvs_get_offset_size (value.size);
++    {
++      out.is_normal = TRUE;
++      return out;
++    }
+ 
+-  last_end = gvs_read_unaligned_le (value.data + value.size -
+-                                    offset_size, offset_size);
++  out.offset_size = gvs_get_offset_size (value.size);
++  last_end = gvs_read_unaligned_le (value.data + value.size - out.offset_size,
++                                    out.offset_size);
+ 
+   if (last_end > value.size)
+-    return 0;
++    return out;  /* offsets not normal */
+ 
+   offsets_array_size = value.size - last_end;
+ 
+-  if (offsets_array_size % offset_size)
+-    return 0;
++  if (offsets_array_size % out.offset_size)
++    return out;  /* offsets not normal */
++
++  out.data_size = last_end;
++  out.array = value.data + last_end;
++  out.length = offsets_array_size / out.offset_size;
++  out.is_normal = TRUE;
+ 
+-  return offsets_array_size / offset_size;
++  return out;
++}
++
++static gsize
++gvs_variable_sized_array_n_children (GVariantSerialised value)
++{
++  return gvs_variable_sized_array_get_frame_offsets (value).length;
+ }
+ 
+ static GVariantSerialised
+@@ -666,8 +698,9 @@ gvs_variable_sized_array_get_child (GVariantSerialised value,
+                                     gsize              index_)
+ {
+   GVariantSerialised child = { 0, };
+-  gsize offset_size;
+-  gsize last_end;
++
++  struct Offsets offsets = gvs_variable_sized_array_get_frame_offsets (value);
++
+   gsize start;
+   gsize end;
+ 
+@@ -675,18 +708,11 @@ gvs_variable_sized_array_get_child (GVariantSerialised value,
+   g_variant_type_info_ref (child.type_info);
+   child.depth = value.depth + 1;
+ 
+-  offset_size = gvs_get_offset_size (value.size);
+-
+-  last_end = gvs_read_unaligned_le (value.data + value.size -
+-                                    offset_size, offset_size);
+-
+   if (index_ > 0)
+     {
+       guint alignment;
+ 
+-      start = gvs_read_unaligned_le (value.data + last_end +
+-                                     (offset_size * (index_ - 1)),
+-                                     offset_size);
++      start = gvs_offsets_get_offset_n (&offsets, index_ - 1);
+ 
+       g_variant_type_info_query (child.type_info, &alignment, NULL);
+       start += (-start) & alignment;
+@@ -694,11 +720,9 @@ gvs_variable_sized_array_get_child (GVariantSerialised value,
+   else
+     start = 0;
+ 
+-  end = gvs_read_unaligned_le (value.data + last_end +
+-                               (offset_size * index_),
+-                               offset_size);
++  end = gvs_offsets_get_offset_n (&offsets, index_);
+ 
+-  if (start < end && end <= value.size && end <= last_end)
++  if (start < end && end <= value.size && end <= offsets.data_size)
+     {
+       child.data = value.data + start;
+       child.size = end - start;
+@@ -770,34 +794,16 @@ static gboolean
+ gvs_variable_sized_array_is_normal (GVariantSerialised value)
+ {
+   GVariantSerialised child = { 0, };
+-  gsize offsets_array_size;
+-  guchar *offsets_array;
+-  guint offset_size;
+   guint alignment;
+-  gsize last_end;
+-  gsize length;
+   gsize offset;
+   gsize i;
+ 
+-  if (value.size == 0)
+-    return TRUE;
+-
+-  offset_size = gvs_get_offset_size (value.size);
+-  last_end = gvs_read_unaligned_le (value.data + value.size -
+-                                    offset_size, offset_size);
++  struct Offsets offsets = gvs_variable_sized_array_get_frame_offsets (value);
+ 
+-  if (last_end > value.size)
++  if (!offsets.is_normal)
+     return FALSE;
+ 
+-  offsets_array_size = value.size - last_end;
+-
+-  if (offsets_array_size % offset_size)
+-    return FALSE;
+-
+-  offsets_array = value.data + value.size - offsets_array_size;
+-  length = offsets_array_size / offset_size;
+-
+-  if (length == 0)
++  if (value.size != 0 && offsets.length == 0)
+     return FALSE;
+ 
+   child.type_info = g_variant_type_info_element (value.type_info);
+@@ -805,14 +811,14 @@ gvs_variable_sized_array_is_normal (GVariantSerialised value)
+   child.depth = value.depth + 1;
+   offset = 0;
+ 
+-  for (i = 0; i < length; i++)
++  for (i = 0; i < offsets.length; i++)
+     {
+       gsize this_end;
+ 
+-      this_end = gvs_read_unaligned_le (offsets_array + offset_size * i,
+-                                        offset_size);
++      this_end = gvs_read_unaligned_le (offsets.array + offsets.offset_size * i,
++                                        offsets.offset_size);
+ 
+-      if (this_end < offset || this_end > last_end)
++      if (this_end < offset || this_end > offsets.data_size)
+         return FALSE;
+ 
+       while (offset & alignment)
+@@ -834,7 +840,7 @@ gvs_variable_sized_array_is_normal (GVariantSerialised value)
+       offset = this_end;
+     }
+ 
+-  g_assert (offset == last_end);
++  g_assert (offset == offsets.data_size);
+ 
+   return TRUE;
+ }
+-- 
+GitLab
+
+
+From 5c27f22aff636766fbc5e49927fd28213629e840 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Tue, 25 Oct 2022 18:05:52 +0100
+Subject: [PATCH 03/18] gvariant: Zero-initialise various GVariantSerialised
+ objects
+
+The following few commits will add a couple of new fields to
+`GVariantSerialised`, and they should be zero-filled by default.
+
+Try and pre-empt that a bit by zero-filling `GVariantSerialised` by
+default in a few places.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2121
+---
+ glib/gvariant.c       |  2 +-
+ glib/tests/gvariant.c | 12 ++++++------
+ 2 files changed, 7 insertions(+), 7 deletions(-)
+
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index 93eb6cb6bc..6912eebe05 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -6001,7 +6001,7 @@ g_variant_byteswap (GVariant *value)
+   if (alignment)
+     /* (potentially) contains multi-byte numeric data */
+     {
+-      GVariantSerialised serialised;
++      GVariantSerialised serialised = { 0, };
+       GVariant *trusted;
+       GBytes *bytes;
+ 
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index 29110e4e24..1a57dc6ef7 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -1440,7 +1440,7 @@ test_maybe (void)
+ 
+     for (flavour = 0; flavour < 8; flavour += alignment)
+       {
+-        GVariantSerialised serialised;
++        GVariantSerialised serialised = { 0, };
+         GVariantSerialised child;
+ 
+         serialised.type_info = type_info;
+@@ -1564,7 +1564,7 @@ test_array (void)
+ 
+     for (flavour = 0; flavour < 8; flavour += alignment)
+       {
+-        GVariantSerialised serialised;
++        GVariantSerialised serialised = { 0, };
+ 
+         serialised.type_info = array_info;
+         serialised.data = flavoured_malloc (needed_size, flavour);
+@@ -1728,7 +1728,7 @@ test_tuple (void)
+ 
+     for (flavour = 0; flavour < 8; flavour += alignment)
+       {
+-        GVariantSerialised serialised;
++        GVariantSerialised serialised = { 0, };
+ 
+         serialised.type_info = type_info;
+         serialised.data = flavoured_malloc (needed_size, flavour);
+@@ -1823,7 +1823,7 @@ test_variant (void)
+ 
+     for (flavour = 0; flavour < 8; flavour += alignment)
+       {
+-        GVariantSerialised serialised;
++        GVariantSerialised serialised = { 0, };
+         GVariantSerialised child;
+ 
+         serialised.type_info = type_info;
+@@ -2270,7 +2270,7 @@ serialise_tree (TreeInstance       *tree,
+ static void
+ test_byteswap (void)
+ {
+-  GVariantSerialised one, two;
++  GVariantSerialised one = { 0, }, two = { 0, };
+   TreeInstance *tree;
+ 
+   tree = tree_instance_new (NULL, 3);
+@@ -2344,7 +2344,7 @@ test_serialiser_children (void)
+ static void
+ test_fuzz (gdouble *fuzziness)
+ {
+-  GVariantSerialised serialised;
++  GVariantSerialised serialised = { 0, };
+   TreeInstance *tree;
+ 
+   /* make an instance */
+-- 
+GitLab
+
+
+From c8067857f7c8fb369ecb30bb534b018b2e2b8f87 Mon Sep 17 00:00:00 2001
+From: William Manley <will@stb-tester.com>
+Date: Mon, 29 Jun 2020 16:59:44 +0100
+Subject: [PATCH 04/18] =?UTF-8?q?gvariant:=20Don=E2=80=99t=20allow=20child?=
+ =?UTF-8?q?=20elements=20to=20overlap=20with=20each=20other?=
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+If different elements of a variable sized array can overlap with each
+other then we can cause a `GVariant` to normalise to a much larger type.
+
+This commit changes the behaviour of `GVariant` with non-normal form data. If
+an invalid frame offset is found all subsequent elements are given their
+default value.
+
+When retrieving an element at index `n` we scan the frame offsets up to index
+`n` and if they are not in order we return an element with the default value
+for that type.  This guarantees that elements don't overlap with each
+other.  We remember the offset we've scanned up to so we don't need to
+repeat this work on subsequent accesses.  We skip these checks for trusted
+data.
+
+Unfortunately this makes random access of untrusted data O(n) — at least
+on first access.  It doesn't affect the algorithmic complexity of accessing
+elements in order, such as when using the `GVariantIter` interface.  Also:
+the cost of validation will be amortised as the `GVariant` instance is
+continued to be used.
+
+I've implemented this with 4 different functions, 1 for each element size,
+rather than looping calling `gvs_read_unaligned_le` in the hope that the
+compiler will find it easy to optimise and should produce fairly tight
+code.
+
+Fixes: #2121
+---
+ glib/gvariant-core.c       | 35 ++++++++++++++++
+ glib/gvariant-serialiser.c | 86 ++++++++++++++++++++++++++++++++++++--
+ glib/gvariant-serialiser.h |  9 ++++
+ glib/tests/gvariant.c      | 45 ++++++++++++++++++++
+ 4 files changed, 172 insertions(+), 3 deletions(-)
+
+diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
+index 70c712ddc0..a75e7db9ea 100644
+--- a/glib/gvariant-core.c
++++ b/glib/gvariant-core.c
+@@ -67,6 +67,7 @@ struct _GVariant
+     {
+       GBytes *bytes;
+       gconstpointer data;
++      gsize ordered_offsets_up_to;
+     } serialised;
+ 
+     struct
+@@ -164,6 +165,24 @@ struct _GVariant
+  *                if .data pointed to the appropriate number of nul
+  *                bytes.
+  *
++ *     .ordered_offsets_up_to: If ordered_offsets_up_to == n this means that all
++ *                             the frame offsets up to and including the frame
++ *                             offset determining the end of element n are in
++ *                             order. This guarantees that the bytes of element
++ *                             n don't overlap with any previous element.
++ *
++ *                             For trusted data this is set to G_MAXSIZE and we
++ *                             don't check that the frame offsets are in order.
++ *
++ *                             Note: This doesn't imply the offsets are good in
++ *                             any way apart from their ordering.  In particular
++ *                             offsets may be out of bounds for this value or
++ *                             may imply that the data overlaps the frame
++ *                             offsets themselves.
++ *
++ *                             This field is only relevant for arrays of non
++ *                             fixed width types.
++ *
+  *   .tree: Only valid when the instance is in tree form.
+  *
+  *          Note that accesses from other threads could result in
+@@ -367,6 +386,7 @@ g_variant_to_serialised (GVariant *value)
+       (gpointer) value->contents.serialised.data,
+       value->size,
+       value->depth,
++      value->contents.serialised.ordered_offsets_up_to,
+     };
+     return serialised;
+   }
+@@ -398,6 +418,7 @@ g_variant_serialise (GVariant *value,
+   serialised.size = value->size;
+   serialised.data = data;
+   serialised.depth = value->depth;
++  serialised.ordered_offsets_up_to = 0;
+ 
+   children = (gpointer *) value->contents.tree.children;
+   n_children = value->contents.tree.n_children;
+@@ -441,6 +462,15 @@ g_variant_fill_gvs (GVariantSerialised *serialised,
+   g_assert (serialised->size == value->size);
+   serialised->depth = value->depth;
+ 
++  if (value->state & STATE_SERIALISED)
++    {
++      serialised->ordered_offsets_up_to = value->contents.serialised.ordered_offsets_up_to;
++    }
++  else
++    {
++      serialised->ordered_offsets_up_to = 0;
++    }
++
+   if (serialised->data)
+     /* g_variant_store() is a public API, so it
+      * it will reacquire the lock if it needs to.
+@@ -483,6 +513,7 @@ g_variant_ensure_serialised (GVariant *value)
+       bytes = g_bytes_new_take (data, value->size);
+       value->contents.serialised.data = g_bytes_get_data (bytes, NULL);
+       value->contents.serialised.bytes = bytes;
++      value->contents.serialised.ordered_offsets_up_to = G_MAXSIZE;
+       value->state |= STATE_SERIALISED;
+     }
+ }
+@@ -563,6 +594,7 @@ g_variant_new_from_bytes (const GVariantType *type,
+   serialised.type_info = value->type_info;
+   serialised.data = (guchar *) g_bytes_get_data (bytes, &serialised.size);
+   serialised.depth = 0;
++  serialised.ordered_offsets_up_to = trusted ? G_MAXSIZE : 0;
+ 
+   if (!g_variant_serialised_check (serialised))
+     {
+@@ -613,6 +645,8 @@ g_variant_new_from_bytes (const GVariantType *type,
+       value->contents.serialised.data = g_bytes_get_data (bytes, &value->size);
+     }
+ 
++  value->contents.serialised.ordered_offsets_up_to = trusted ? G_MAXSIZE : 0;
++
+   g_clear_pointer (&owned_bytes, g_bytes_unref);
+ 
+   return value;
+@@ -1132,6 +1166,7 @@ g_variant_get_child_value (GVariant *value,
+     child->contents.serialised.bytes =
+       g_bytes_ref (value->contents.serialised.bytes);
+     child->contents.serialised.data = s_child.data;
++    child->contents.serialised.ordered_offsets_up_to = s_child.ordered_offsets_up_to;
+ 
+     return child;
+   }
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index 09492e4526..1aa2b8fa9b 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -1,6 +1,7 @@
+ /*
+  * Copyright © 2007, 2008 Ryan Lortie
+  * Copyright © 2010 Codethink Limited
++ * Copyright © 2020 William Manley
+  *
+  * SPDX-License-Identifier: LGPL-2.1-or-later
+  *
+@@ -266,6 +267,7 @@ gvs_fixed_sized_maybe_get_child (GVariantSerialised value,
+   value.type_info = g_variant_type_info_element (value.type_info);
+   g_variant_type_info_ref (value.type_info);
+   value.depth++;
++  value.ordered_offsets_up_to = 0;
+ 
+   return value;
+ }
+@@ -297,7 +299,7 @@ gvs_fixed_sized_maybe_serialise (GVariantSerialised        value,
+ {
+   if (n_children)
+     {
+-      GVariantSerialised child = { NULL, value.data, value.size, value.depth + 1 };
++      GVariantSerialised child = { NULL, value.data, value.size, value.depth + 1, 0 };
+ 
+       gvs_filler (&child, children[0]);
+     }
+@@ -319,6 +321,7 @@ gvs_fixed_sized_maybe_is_normal (GVariantSerialised value)
+       /* proper element size: "Just".  recurse to the child. */
+       value.type_info = g_variant_type_info_element (value.type_info);
+       value.depth++;
++      value.ordered_offsets_up_to = 0;
+ 
+       return g_variant_serialised_is_normal (value);
+     }
+@@ -360,6 +363,7 @@ gvs_variable_sized_maybe_get_child (GVariantSerialised value,
+     value.data = NULL;
+ 
+   value.depth++;
++  value.ordered_offsets_up_to = 0;
+ 
+   return value;
+ }
+@@ -390,7 +394,7 @@ gvs_variable_sized_maybe_serialise (GVariantSerialised        value,
+ {
+   if (n_children)
+     {
+-      GVariantSerialised child = { NULL, value.data, value.size - 1, value.depth + 1 };
++      GVariantSerialised child = { NULL, value.data, value.size - 1, value.depth + 1, 0 };
+ 
+       /* write the data for the child.  */
+       gvs_filler (&child, children[0]);
+@@ -410,6 +414,7 @@ gvs_variable_sized_maybe_is_normal (GVariantSerialised value)
+   value.type_info = g_variant_type_info_element (value.type_info);
+   value.size--;
+   value.depth++;
++  value.ordered_offsets_up_to = 0;
+ 
+   return g_variant_serialised_is_normal (value);
+ }
+@@ -693,6 +698,32 @@ gvs_variable_sized_array_n_children (GVariantSerialised value)
+   return gvs_variable_sized_array_get_frame_offsets (value).length;
+ }
+ 
++/* Find the index of the first out-of-order element in @data, assuming that
++ * @data is an array of elements of given @type, starting at index @start and
++ * containing a further @len-@start elements. */
++#define DEFINE_FIND_UNORDERED(type) \
++  static gsize \
++  find_unordered_##type (const guint8 *data, gsize start, gsize len) \
++  { \
++    gsize off; \
++    type current, previous; \
++    \
++    memcpy (&previous, data + start * sizeof (current), sizeof (current)); \
++    for (off = (start + 1) * sizeof (current); off < len * sizeof (current); off += sizeof (current)) \
++      { \
++        memcpy (&current, data + off, sizeof (current)); \
++        if (current < previous) \
++          break; \
++        previous = current; \
++      } \
++    return off / sizeof (current) - 1; \
++  }
++
++DEFINE_FIND_UNORDERED (guint8);
++DEFINE_FIND_UNORDERED (guint16);
++DEFINE_FIND_UNORDERED (guint32);
++DEFINE_FIND_UNORDERED (guint64);
++
+ static GVariantSerialised
+ gvs_variable_sized_array_get_child (GVariantSerialised value,
+                                     gsize              index_)
+@@ -708,6 +739,49 @@ gvs_variable_sized_array_get_child (GVariantSerialised value,
+   g_variant_type_info_ref (child.type_info);
+   child.depth = value.depth + 1;
+ 
++  /* If the requested @index_ is beyond the set of indices whose framing offsets
++   * have been checked, check the remaining offsets to see whether they’re
++   * normal (in order, no overlapping array elements). */
++  if (index_ > value.ordered_offsets_up_to)
++    {
++      switch (offsets.offset_size)
++        {
++        case 1:
++          {
++            value.ordered_offsets_up_to = find_unordered_guint8 (
++                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++            break;
++          }
++        case 2:
++          {
++            value.ordered_offsets_up_to = find_unordered_guint16 (
++                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++            break;
++          }
++        case 4:
++          {
++            value.ordered_offsets_up_to = find_unordered_guint32 (
++                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++            break;
++          }
++        case 8:
++          {
++            value.ordered_offsets_up_to = find_unordered_guint64 (
++                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++            break;
++          }
++        default:
++          /* gvs_get_offset_size() only returns maximum 8 */
++          g_assert_not_reached ();
++        }
++    }
++
++  if (index_ > value.ordered_offsets_up_to)
++    {
++      /* Offsets are invalid somewhere, so return an empty child. */
++      return child;
++    }
++
+   if (index_ > 0)
+     {
+       guint alignment;
+@@ -842,6 +916,9 @@ gvs_variable_sized_array_is_normal (GVariantSerialised value)
+ 
+   g_assert (offset == offsets.data_size);
+ 
++  /* All offsets have now been checked. */
++  value.ordered_offsets_up_to = G_MAXSIZE;
++
+   return TRUE;
+ }
+ 
+@@ -1074,7 +1151,7 @@ gvs_tuple_is_normal (GVariantSerialised value)
+   for (i = 0; i < length; i++)
+     {
+       const GVariantMemberInfo *member_info;
+-      GVariantSerialised child;
++      GVariantSerialised child = { 0, };
+       gsize fixed_size;
+       guint alignment;
+       gsize end;
+@@ -1134,6 +1211,9 @@ gvs_tuple_is_normal (GVariantSerialised value)
+       offset = end;
+     }
+ 
++  /* All element bounds have been checked above. */
++  value.ordered_offsets_up_to = G_MAXSIZE;
++
+   {
+     gsize fixed_size;
+     guint alignment;
+diff --git a/glib/gvariant-serialiser.h b/glib/gvariant-serialiser.h
+index 6ced7e3d6c..a1bccb834b 100644
+--- a/glib/gvariant-serialiser.h
++++ b/glib/gvariant-serialiser.h
+@@ -31,6 +31,15 @@ typedef struct
+   guchar           *data;
+   gsize             size;
+   gsize             depth;  /* same semantics as GVariant.depth */
++
++  /* If ordered_offsets_up_to == n this means that all the frame offsets up to and
++   * including the frame offset determining the end of element n are in order.
++   * This guarantees that the bytes of element n don't overlap with any previous
++   * element.
++   *
++   * This is both read and set by g_variant_serialised_get_child for arrays of
++   * non-fixed-width types */
++  gsize             ordered_offsets_up_to;
+ } GVariantSerialised;
+ 
+ /* deserialization */
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index 1a57dc6ef7..c759e8d701 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -1,5 +1,6 @@
+ /*
+  * Copyright © 2010 Codethink Limited
++ * Copyright © 2020 William Manley
+  *
+  * SPDX-License-Identifier: LGPL-2.1-or-later
+  *
+@@ -1281,6 +1282,7 @@ random_instance_filler (GVariantSerialised *serialised,
+     serialised->size = instance->size;
+ 
+   serialised->depth = 0;
++  serialised->ordered_offsets_up_to = 0;
+ 
+   g_assert_true (serialised->type_info == instance->type_info);
+   g_assert_cmpuint (serialised->size, ==, instance->size);
+@@ -5131,6 +5133,47 @@ test_normal_checking_array_offsets (void)
+   g_variant_unref (variant);
+ }
+ 
++/* This is a regression test that we can't have non-normal values that take up
++ * significantly more space than the normal equivalent, by specifying the
++ * offset table entries so that array elements overlap.
++ *
++ * See https://gitlab.gnome.org/GNOME/glib/-/issues/2121#note_832242 */
++static void
++test_normal_checking_array_offsets2 (void)
++{
++  const guint8 data[] = {
++    'h', 'i', '\0',
++    0x03, 0x00, 0x03,
++    0x06, 0x00, 0x06,
++    0x09, 0x00, 0x09,
++    0x0c, 0x00, 0x0c,
++    0x0f, 0x00, 0x0f,
++    0x12, 0x00, 0x12,
++    0x15, 0x00, 0x15,
++  };
++  gsize size = sizeof (data);
++  const GVariantType *aaaaaaas = G_VARIANT_TYPE ("aaaaaaas");
++  GVariant *variant = NULL;
++  GVariant *normal_variant = NULL;
++  GVariant *expected = NULL;
++
++  variant = g_variant_new_from_data (aaaaaaas, data, size, FALSE, NULL, NULL);
++  g_assert_nonnull (variant);
++
++  normal_variant = g_variant_get_normal_form (variant);
++  g_assert_nonnull (normal_variant);
++  g_assert_cmpuint (g_variant_get_size (normal_variant), <=, size * 2);
++
++  expected = g_variant_new_parsed (
++      "[[[[[[['hi', '', ''], [], []], [], []], [], []], [], []], [], []], [], []]");
++  g_assert_cmpvariant (expected, variant);
++  g_assert_cmpvariant (expected, normal_variant);
++
++  g_variant_unref (expected);
++  g_variant_unref (normal_variant);
++  g_variant_unref (variant);
++}
++
+ /* Test that a tuple with invalidly large values in its offset table is
+  * normalised successfully without looping infinitely. */
+ static void
+@@ -5299,6 +5342,8 @@ main (int argc, char **argv)
+                    test_normal_checking_tuples);
+   g_test_add_func ("/gvariant/normal-checking/array-offsets",
+                    test_normal_checking_array_offsets);
++  g_test_add_func ("/gvariant/normal-checking/array-offsets2",
++                   test_normal_checking_array_offsets2);
+   g_test_add_func ("/gvariant/normal-checking/tuple-offsets",
+                    test_normal_checking_tuple_offsets);
+   g_test_add_func ("/gvariant/normal-checking/empty-object-path",
+-- 
+GitLab
+
+
+From 66e7c10aa1ec3102c49186f83671a5f0461ffbc0 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Fri, 7 Jan 2022 15:03:52 +0000
+Subject: [PATCH 05/18] gvariant-serialiser: Factor out code to get bounds of a
+ tuple member
+
+This introduces no functional changes.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2121
+---
+ glib/gvariant-serialiser.c | 73 ++++++++++++++++++++++++--------------
+ 1 file changed, 46 insertions(+), 27 deletions(-)
+
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index 1aa2b8fa9b..a518117e3c 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -944,6 +944,51 @@ gvs_variable_sized_array_is_normal (GVariantSerialised value)
+  * for the tuple.  See the notes in gvarianttypeinfo.h.
+  */
+ 
++static void
++gvs_tuple_get_member_bounds (GVariantSerialised  value,
++                             gsize               index_,
++                             gsize               offset_size,
++                             gsize              *out_member_start,
++                             gsize              *out_member_end)
++{
++  const GVariantMemberInfo *member_info;
++  gsize member_start, member_end;
++
++  member_info = g_variant_type_info_member_info (value.type_info, index_);
++
++  if (member_info->i + 1)
++    member_start = gvs_read_unaligned_le (value.data + value.size -
++                                          offset_size * (member_info->i + 1),
++                                          offset_size);
++  else
++    member_start = 0;
++
++  member_start += member_info->a;
++  member_start &= member_info->b;
++  member_start |= member_info->c;
++
++  if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_LAST)
++    member_end = value.size - offset_size * (member_info->i + 1);
++
++  else if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_FIXED)
++    {
++      gsize fixed_size;
++
++      g_variant_type_info_query (member_info->type_info, NULL, &fixed_size);
++      member_end = member_start + fixed_size;
++    }
++
++  else /* G_VARIANT_MEMBER_ENDING_OFFSET */
++    member_end = gvs_read_unaligned_le (value.data + value.size -
++                                        offset_size * (member_info->i + 2),
++                                        offset_size);
++
++  if (out_member_start != NULL)
++    *out_member_start = member_start;
++  if (out_member_end != NULL)
++    *out_member_end = member_end;
++}
++
+ static gsize
+ gvs_tuple_n_children (GVariantSerialised value)
+ {
+@@ -999,33 +1044,7 @@ gvs_tuple_get_child (GVariantSerialised value,
+         }
+     }
+ 
+-  if (member_info->i + 1)
+-    start = gvs_read_unaligned_le (value.data + value.size -
+-                                   offset_size * (member_info->i + 1),
+-                                   offset_size);
+-  else
+-    start = 0;
+-
+-  start += member_info->a;
+-  start &= member_info->b;
+-  start |= member_info->c;
+-
+-  if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_LAST)
+-    end = value.size - offset_size * (member_info->i + 1);
+-
+-  else if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_FIXED)
+-    {
+-      gsize fixed_size;
+-
+-      g_variant_type_info_query (child.type_info, NULL, &fixed_size);
+-      end = start + fixed_size;
+-      child.size = fixed_size;
+-    }
+-
+-  else /* G_VARIANT_MEMBER_ENDING_OFFSET */
+-    end = gvs_read_unaligned_le (value.data + value.size -
+-                                 offset_size * (member_info->i + 2),
+-                                 offset_size);
++  gvs_tuple_get_member_bounds (value, index_, offset_size, &start, &end);
+ 
+   /* The child should not extend into the offset table. */
+   if (index_ != g_variant_type_info_n_members (value.type_info) - 1)
+-- 
+GitLab
+
+
+From a62a6b5d3e53b30a4628db2a077ab9ed03605748 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Fri, 7 Jan 2022 16:37:29 +0000
+Subject: [PATCH 06/18] gvariant-serialiser: Rework child size calculation
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This reduces a few duplicate calls to `g_variant_type_info_query()` and
+explains why they’re needed.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2121
+---
+ glib/gvariant-serialiser.c | 31 +++++++++----------------------
+ 1 file changed, 9 insertions(+), 22 deletions(-)
+
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index a518117e3c..d32e255480 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -1009,14 +1009,18 @@ gvs_tuple_get_child (GVariantSerialised value,
+   child.depth = value.depth + 1;
+   offset_size = gvs_get_offset_size (value.size);
+ 
++  /* Ensure the size is set for fixed-sized children, or
++   * g_variant_serialised_check() will fail, even if we return
++   * (child.data == NULL) to indicate an error. */
++  if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_FIXED)
++    g_variant_type_info_query (child.type_info, NULL, &child.size);
++
+   /* tuples are the only (potentially) fixed-sized containers, so the
+    * only ones that have to deal with the possibility of having %NULL
+    * data with a non-zero %size if errors occurred elsewhere.
+    */
+   if G_UNLIKELY (value.data == NULL && value.size != 0)
+     {
+-      g_variant_type_info_query (child.type_info, NULL, &child.size);
+-
+       /* this can only happen in fixed-sized tuples,
+        * so the child must also be fixed sized.
+        */
+@@ -1034,29 +1038,12 @@ gvs_tuple_get_child (GVariantSerialised value,
+   else
+     {
+       if (offset_size * (member_info->i + 1) > value.size)
+-        {
+-          /* if the child is fixed size, return its size.
+-           * if child is not fixed-sized, return size = 0.
+-           */
+-          g_variant_type_info_query (child.type_info, NULL, &child.size);
+-
+-          return child;
+-        }
++        return child;
+     }
+ 
+-  gvs_tuple_get_member_bounds (value, index_, offset_size, &start, &end);
+-
+   /* The child should not extend into the offset table. */
+-  if (index_ != g_variant_type_info_n_members (value.type_info) - 1)
+-    {
+-      GVariantSerialised last_child;
+-      last_child = gvs_tuple_get_child (value,
+-                                        g_variant_type_info_n_members (value.type_info) - 1);
+-      last_end = last_child.data + last_child.size - value.data;
+-      g_variant_type_info_unref (last_child.type_info);
+-    }
+-  else
+-    last_end = end;
++  gvs_tuple_get_member_bounds (value, index_, offset_size, &start, &end);
++  gvs_tuple_get_member_bounds (value, g_variant_type_info_n_members (value.type_info) - 1, offset_size, NULL, &last_end);
+ 
+   if (start < end && end <= value.size && end <= last_end)
+     {
+-- 
+GitLab
+
+
+From 2d55b3b74b1bc256e91a9d0d59120570376e6acc Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Fri, 7 Jan 2022 16:42:14 +0000
+Subject: [PATCH 07/18] =?UTF-8?q?gvariant:=20Don=E2=80=99t=20allow=20child?=
+ =?UTF-8?q?=20elements=20of=20a=20tuple=20to=20overlap=20each=20other?=
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This is similar to the earlier commit which prevents child elements of a
+variable-sized array from overlapping each other, but this time for
+tuples. It is based heavily on ideas by William Manley.
+
+Tuples are slightly different from variable-sized arrays in that they
+contain a mixture of fixed and variable sized elements. All but one of
+the variable sized elements have an entry in the frame offsets table.
+This means that if we were to just check the ordering of the frame
+offsets table, the variable sized elements could still overlap
+interleaving fixed sized elements, which would be bad.
+
+Therefore we have to check the elements rather than the frame offsets.
+
+The logic of checking the elements up to the index currently being
+requested, and caching the result in `ordered_offsets_up_to`, means that
+the algorithmic cost implications are the same for this commit as for
+variable-sized arrays: an O(N) cost for these checks is amortised out
+over N accesses to O(1) per access.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Fixes: #2121
+---
+ glib/gvariant-core.c       |   6 +-
+ glib/gvariant-serialiser.c |  40 ++++++++
+ glib/gvariant-serialiser.h |   7 +-
+ glib/gvariant.c            |   1 +
+ glib/tests/gvariant.c      | 181 +++++++++++++++++++++++++++++++++++++
+ 5 files changed, 232 insertions(+), 3 deletions(-)
+
+diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
+index a75e7db9ea..c0e1931c39 100644
+--- a/glib/gvariant-core.c
++++ b/glib/gvariant-core.c
+@@ -1,6 +1,7 @@
+ /*
+  * Copyright © 2007, 2008 Ryan Lortie
+  * Copyright © 2010 Codethink Limited
++ * Copyright © 2022 Endless OS Foundation, LLC
+  *
+  * SPDX-License-Identifier: LGPL-2.1-or-later
+  *
+@@ -181,7 +182,7 @@ struct _GVariant
+  *                             offsets themselves.
+  *
+  *                             This field is only relevant for arrays of non
+- *                             fixed width types.
++ *                             fixed width types and for tuples.
+  *
+  *   .tree: Only valid when the instance is in tree form.
+  *
+@@ -1141,6 +1142,9 @@ g_variant_get_child_value (GVariant *value,
+      */
+     s_child = g_variant_serialised_get_child (serialised, index_);
+ 
++    /* Update the cached ordered_offsets_up_to, since @serialised will be thrown away when this function exits */
++    value->contents.serialised.ordered_offsets_up_to = MAX (value->contents.serialised.ordered_offsets_up_to, serialised.ordered_offsets_up_to);
++
+     /* Check whether this would cause nesting too deep. If so, return a fake
+      * child. The only situation we expect this to happen in is with a variant,
+      * as all other deeply-nested types have a static type, and hence should
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index d32e255480..fda59d6843 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -944,6 +944,10 @@ gvs_variable_sized_array_is_normal (GVariantSerialised value)
+  * for the tuple.  See the notes in gvarianttypeinfo.h.
+  */
+ 
++/* Note: This doesn’t guarantee that @out_member_end >= @out_member_start; that
++ * condition may not hold true for invalid serialised variants. The caller is
++ * responsible for checking the returned values and handling invalid ones
++ * appropriately. */
+ static void
+ gvs_tuple_get_member_bounds (GVariantSerialised  value,
+                              gsize               index_,
+@@ -1030,6 +1034,42 @@ gvs_tuple_get_child (GVariantSerialised value,
+       return child;
+     }
+ 
++  /* If the requested @index_ is beyond the set of indices whose framing offsets
++   * have been checked, check the remaining offsets to see whether they’re
++   * normal (in order, no overlapping tuple elements).
++   *
++   * Unlike the checks in gvs_variable_sized_array_get_child(), we have to check
++   * all the tuple *elements* here, not just all the framing offsets, since
++   * tuples contain a mix of elements which use framing offsets and ones which
++   * don’t. None of them are allowed to overlap. */
++  if (index_ > value.ordered_offsets_up_to)
++    {
++      gsize i, prev_i_end = 0;
++
++      if (value.ordered_offsets_up_to > 0)
++        gvs_tuple_get_member_bounds (value, value.ordered_offsets_up_to - 1, offset_size, NULL, &prev_i_end);
++
++      for (i = value.ordered_offsets_up_to; i <= index_; i++)
++        {
++          gsize i_start, i_end;
++
++          gvs_tuple_get_member_bounds (value, i, offset_size, &i_start, &i_end);
++
++          if (i_start > i_end || i_start < prev_i_end || i_end > value.size)
++            break;
++
++          prev_i_end = i_end;
++        }
++
++      value.ordered_offsets_up_to = i - 1;
++    }
++
++  if (index_ > value.ordered_offsets_up_to)
++    {
++      /* Offsets are invalid somewhere, so return an empty child. */
++      return child;
++    }
++
+   if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_OFFSET)
+     {
+       if (offset_size * (member_info->i + 2) > value.size)
+diff --git a/glib/gvariant-serialiser.h b/glib/gvariant-serialiser.h
+index a1bccb834b..661bd8fd1b 100644
+--- a/glib/gvariant-serialiser.h
++++ b/glib/gvariant-serialiser.h
+@@ -37,8 +37,11 @@ typedef struct
+    * This guarantees that the bytes of element n don't overlap with any previous
+    * element.
+    *
+-   * This is both read and set by g_variant_serialised_get_child for arrays of
+-   * non-fixed-width types */
++   * This is both read and set by g_variant_serialised_get_child() for arrays of
++   * non-fixed-width types, and for tuples.
++   *
++   * Even when dealing with tuples, @ordered_offsets_up_to is an element index,
++   * rather than an index into the frame offsets. */
+   gsize             ordered_offsets_up_to;
+ } GVariantSerialised;
+ 
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index 6912eebe05..16af7a5678 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -6010,6 +6010,7 @@ g_variant_byteswap (GVariant *value)
+       serialised.size = g_variant_get_size (trusted);
+       serialised.data = g_malloc (serialised.size);
+       serialised.depth = g_variant_get_depth (trusted);
++      serialised.ordered_offsets_up_to = G_MAXSIZE;  /* operating on the normal form */
+       g_variant_store (trusted, serialised.data);
+       g_variant_unref (trusted);
+ 
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index c759e8d701..0cb69d4b70 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -1,6 +1,7 @@
+ /*
+  * Copyright © 2010 Codethink Limited
+  * Copyright © 2020 William Manley
++ * Copyright © 2022 Endless OS Foundation, LLC
+  *
+  * SPDX-License-Identifier: LGPL-2.1-or-later
+  *
+@@ -1449,6 +1450,7 @@ test_maybe (void)
+         serialised.data = flavoured_malloc (needed_size, flavour);
+         serialised.size = needed_size;
+         serialised.depth = 0;
++        serialised.ordered_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised,
+                                         random_instance_filler,
+@@ -1572,6 +1574,7 @@ test_array (void)
+         serialised.data = flavoured_malloc (needed_size, flavour);
+         serialised.size = needed_size;
+         serialised.depth = 0;
++        serialised.ordered_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised, random_instance_filler,
+                                         (gpointer *) instances, n_children);
+@@ -1736,6 +1739,7 @@ test_tuple (void)
+         serialised.data = flavoured_malloc (needed_size, flavour);
+         serialised.size = needed_size;
+         serialised.depth = 0;
++        serialised.ordered_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised, random_instance_filler,
+                                         (gpointer *) instances, n_children);
+@@ -1832,6 +1836,7 @@ test_variant (void)
+         serialised.data = flavoured_malloc (needed_size, flavour);
+         serialised.size = needed_size;
+         serialised.depth = 0;
++        serialised.ordered_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised, random_instance_filler,
+                                         (gpointer *) &instance, 1);
+@@ -5198,6 +5203,176 @@ test_normal_checking_tuple_offsets (void)
+   g_variant_unref (variant);
+ }
+ 
++/* This is a regression test that we can't have non-normal values that take up
++ * significantly more space than the normal equivalent, by specifying the
++ * offset table entries so that tuple elements overlap.
++ *
++ * See https://gitlab.gnome.org/GNOME/glib/-/issues/2121#note_838503 and
++ * https://gitlab.gnome.org/GNOME/glib/-/issues/2121#note_838513 */
++static void
++test_normal_checking_tuple_offsets2 (void)
++{
++  const GVariantType *data_type = G_VARIANT_TYPE ("(yyaiyyaiyy)");
++  const guint8 data[] = {
++    0x12, 0x34, 0x56, 0x78, 0x01,
++    /*
++         ^───────────────────┘
++
++    ^^^^^^^^^^                   1st yy
++          ^^^^^^^^^^             2nd yy
++                ^^^^^^^^^^       3rd yy
++                            ^^^^ Framing offsets
++     */
++
++  /* If this variant was encoded normally, it would be something like this:
++   * 0x12, 0x34,  pad,  pad, [array bytes], 0x56, 0x78,  pad,  pad, [array bytes], 0x9A, 0xBC, 0xXX
++   *                                      ^─────────────────────────────────────────────────────┘
++   *
++   * ^^^^^^^^^^                                                                                     1st yy
++   *                                        ^^^^^^^^^^                                              2nd yy
++   *                                                                               ^^^^^^^^^^       3rd yy
++   *                                                                                           ^^^^ Framing offsets
++   */
++  };
++  gsize size = sizeof (data);
++  GVariant *variant = NULL;
++  GVariant *normal_variant = NULL;
++  GVariant *expected = NULL;
++
++  variant = g_variant_new_from_data (data_type, data, size, FALSE, NULL, NULL);
++  g_assert_nonnull (variant);
++
++  normal_variant = g_variant_get_normal_form (variant);
++  g_assert_nonnull (normal_variant);
++  g_assert_cmpuint (g_variant_get_size (normal_variant), <=, size * 3);
++
++  expected = g_variant_new_parsed (
++      "@(yyaiyyaiyy) (0x12, 0x34, [], 0x00, 0x00, [], 0x00, 0x00)");
++  g_assert_cmpvariant (expected, variant);
++  g_assert_cmpvariant (expected, normal_variant);
++
++  g_variant_unref (expected);
++  g_variant_unref (normal_variant);
++  g_variant_unref (variant);
++}
++
++/* This is a regression test that overlapping entries in the offset table are
++ * decoded consistently, even though they’re non-normal.
++ *
++ * See https://gitlab.gnome.org/GNOME/glib/-/issues/2121#note_910935 */
++static void
++test_normal_checking_tuple_offsets3 (void)
++{
++  /* The expected decoding of this non-normal byte stream is complex. See
++   * section 2.7.3 (Handling Non-Normal Serialised Data) of the GVariant
++   * specification.
++   *
++   * The rule “Child Values Overlapping Framing Offsets” from the specification
++   * says that the first `ay` must be decoded as `[0x01]` even though it
++   * overlaps the first byte of the offset table. However, since commit
++   * 7eedcd76f7d5b8c98fa60013e1fe6e960bf19df3, GLib explicitly doesn’t allow
++   * this as it’s exploitable. So the first `ay` must be given a default value.
++   *
++   * The second and third `ay`s must be given default values because of rule
++   * “End Boundary Precedes Start Boundary”.
++   *
++   * The `i` must be given a default value because of rule “Start or End
++   * Boundary of a Child Falls Outside the Container”.
++   */
++  const GVariantType *data_type = G_VARIANT_TYPE ("(ayayiay)");
++  const guint8 data[] = {
++    0x01, 0x00, 0x02,
++    /*
++               ^──┘
++
++    ^^^^^^^^^^                   1st ay, bytes 0-2 (but given a default value anyway, see above)
++                                 2nd ay, bytes 2-0
++                                     i,  bytes 0-4
++                                 3rd ay, bytes 4-1
++          ^^^^^^^^^^ Framing offsets
++     */
++  };
++  gsize size = sizeof (data);
++  GVariant *variant = NULL;
++  GVariant *normal_variant = NULL;
++  GVariant *expected = NULL;
++
++  variant = g_variant_new_from_data (data_type, data, size, FALSE, NULL, NULL);
++  g_assert_nonnull (variant);
++
++  g_assert_false (g_variant_is_normal_form (variant));
++
++  normal_variant = g_variant_get_normal_form (variant);
++  g_assert_nonnull (normal_variant);
++  g_assert_cmpuint (g_variant_get_size (normal_variant), <=, size * 3);
++
++  expected = g_variant_new_parsed ("@(ayayiay) ([], [], 0, [])");
++  g_assert_cmpvariant (expected, variant);
++  g_assert_cmpvariant (expected, normal_variant);
++
++  g_variant_unref (expected);
++  g_variant_unref (normal_variant);
++  g_variant_unref (variant);
++}
++
++/* This is a regression test that overlapping entries in the offset table are
++ * decoded consistently, even though they’re non-normal.
++ *
++ * See https://gitlab.gnome.org/GNOME/glib/-/issues/2121#note_910935 */
++static void
++test_normal_checking_tuple_offsets4 (void)
++{
++  /* The expected decoding of this non-normal byte stream is complex. See
++   * section 2.7.3 (Handling Non-Normal Serialised Data) of the GVariant
++   * specification.
++   *
++   * The rule “Child Values Overlapping Framing Offsets” from the specification
++   * says that the first `ay` must be decoded as `[0x01]` even though it
++   * overlaps the first byte of the offset table. However, since commit
++   * 7eedcd76f7d5b8c98fa60013e1fe6e960bf19df3, GLib explicitly doesn’t allow
++   * this as it’s exploitable. So the first `ay` must be given a default value.
++   *
++   * The second `ay` must be given a default value because of rule “End Boundary
++   * Precedes Start Boundary”.
++   *
++   * The third `ay` must be given a default value because its framing offsets
++   * overlap that of the first `ay`.
++   */
++  const GVariantType *data_type = G_VARIANT_TYPE ("(ayayay)");
++  const guint8 data[] = {
++    0x01, 0x00, 0x02,
++    /*
++               ^──┘
++
++    ^^^^^^^^^^                   1st ay, bytes 0-2 (but given a default value anyway, see above)
++                                 2nd ay, bytes 2-0
++                                 3rd ay, bytes 0-1
++          ^^^^^^^^^^ Framing offsets
++     */
++  };
++  gsize size = sizeof (data);
++  GVariant *variant = NULL;
++  GVariant *normal_variant = NULL;
++  GVariant *expected = NULL;
++
++  variant = g_variant_new_from_data (data_type, data, size, FALSE, NULL, NULL);
++  g_assert_nonnull (variant);
++
++  g_assert_false (g_variant_is_normal_form (variant));
++
++  normal_variant = g_variant_get_normal_form (variant);
++  g_assert_nonnull (normal_variant);
++  g_assert_cmpuint (g_variant_get_size (normal_variant), <=, size * 3);
++
++  expected = g_variant_new_parsed ("@(ayayay) ([], [], [])");
++  g_assert_cmpvariant (expected, variant);
++  g_assert_cmpvariant (expected, normal_variant);
++
++  g_variant_unref (expected);
++  g_variant_unref (normal_variant);
++  g_variant_unref (variant);
++}
++
+ /* Test that an empty object path is normalised successfully to the base object
+  * path, ‘/’. */
+ static void
+@@ -5346,6 +5521,12 @@ main (int argc, char **argv)
+                    test_normal_checking_array_offsets2);
+   g_test_add_func ("/gvariant/normal-checking/tuple-offsets",
+                    test_normal_checking_tuple_offsets);
++  g_test_add_func ("/gvariant/normal-checking/tuple-offsets2",
++                   test_normal_checking_tuple_offsets2);
++  g_test_add_func ("/gvariant/normal-checking/tuple-offsets3",
++                   test_normal_checking_tuple_offsets3);
++  g_test_add_func ("/gvariant/normal-checking/tuple-offsets4",
++                   test_normal_checking_tuple_offsets4);
+   g_test_add_func ("/gvariant/normal-checking/empty-object-path",
+                    test_normal_checking_empty_object_path);
+ 
+-- 
+GitLab
+
+
+From a6cb880af0a0932493ba096f01990e694e2c5b72 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Tue, 25 Oct 2022 15:14:14 +0100
+Subject: [PATCH 08/18] gvariant: Track checked and ordered offsets
+ independently
+
+The past few commits introduced the concept of known-good offsets in the
+offset table (which is used for variable-width arrays and tuples).
+Good offsets are ones which are non-overlapping with all the previous
+offsets in the table.
+
+If a bad offset is encountered when indexing into the array or tuple,
+the cached known-good offset index will not be increased. In this way,
+all child variants at and beyond the first bad offset can be returned as
+default values rather than dereferencing potentially invalid data.
+
+In this case, there was no information about the fact that the indexes
+between the highest known-good index and the requested one had been
+checked already. That could lead to a pathological case where an offset
+table with an invalid first offset is repeatedly checked in full when
+trying to access higher-indexed children.
+
+Avoid that by storing the index of the highest checked offset in the
+table, as well as the index of the highest good/ordered offset.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2121
+---
+ glib/gvariant-core.c       | 28 ++++++++++++++++++++++++
+ glib/gvariant-serialiser.c | 44 +++++++++++++++++++++++++++-----------
+ glib/gvariant-serialiser.h |  9 ++++++++
+ glib/gvariant.c            |  1 +
+ glib/tests/gvariant.c      |  5 +++++
+ 5 files changed, 75 insertions(+), 12 deletions(-)
+
+diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
+index c0e1931c39..e61242f763 100644
+--- a/glib/gvariant-core.c
++++ b/glib/gvariant-core.c
+@@ -69,6 +69,7 @@ struct _GVariant
+       GBytes *bytes;
+       gconstpointer data;
+       gsize ordered_offsets_up_to;
++      gsize checked_offsets_up_to;
+     } serialised;
+ 
+     struct
+@@ -184,6 +185,24 @@ struct _GVariant
+  *                             This field is only relevant for arrays of non
+  *                             fixed width types and for tuples.
+  *
++ *     .checked_offsets_up_to: Similarly to .ordered_offsets_up_to, this stores
++ *                             the index of the highest element, n, whose frame
++ *                             offsets (and all the preceding frame offsets)
++ *                             have been checked for validity.
++ *
++ *                             It is always the case that
++ *                             .checked_offsets_up_to ≥ .ordered_offsets_up_to.
++ *
++ *                             If .checked_offsets_up_to == .ordered_offsets_up_to,
++ *                             then a bad offset has not been found so far.
++ *
++ *                             If .checked_offsets_up_to > .ordered_offsets_up_to,
++ *                             then a bad offset has been found at
++ *                             (.ordered_offsets_up_to + 1).
++ *
++ *                             This field is only relevant for arrays of non
++ *                             fixed width types and for tuples.
++ *
+  *   .tree: Only valid when the instance is in tree form.
+  *
+  *          Note that accesses from other threads could result in
+@@ -388,6 +407,7 @@ g_variant_to_serialised (GVariant *value)
+       value->size,
+       value->depth,
+       value->contents.serialised.ordered_offsets_up_to,
++      value->contents.serialised.checked_offsets_up_to,
+     };
+     return serialised;
+   }
+@@ -420,6 +440,7 @@ g_variant_serialise (GVariant *value,
+   serialised.data = data;
+   serialised.depth = value->depth;
+   serialised.ordered_offsets_up_to = 0;
++  serialised.checked_offsets_up_to = 0;
+ 
+   children = (gpointer *) value->contents.tree.children;
+   n_children = value->contents.tree.n_children;
+@@ -466,10 +487,12 @@ g_variant_fill_gvs (GVariantSerialised *serialised,
+   if (value->state & STATE_SERIALISED)
+     {
+       serialised->ordered_offsets_up_to = value->contents.serialised.ordered_offsets_up_to;
++      serialised->checked_offsets_up_to = value->contents.serialised.checked_offsets_up_to;
+     }
+   else
+     {
+       serialised->ordered_offsets_up_to = 0;
++      serialised->checked_offsets_up_to = 0;
+     }
+ 
+   if (serialised->data)
+@@ -515,6 +538,7 @@ g_variant_ensure_serialised (GVariant *value)
+       value->contents.serialised.data = g_bytes_get_data (bytes, NULL);
+       value->contents.serialised.bytes = bytes;
+       value->contents.serialised.ordered_offsets_up_to = G_MAXSIZE;
++      value->contents.serialised.checked_offsets_up_to = G_MAXSIZE;
+       value->state |= STATE_SERIALISED;
+     }
+ }
+@@ -596,6 +620,7 @@ g_variant_new_from_bytes (const GVariantType *type,
+   serialised.data = (guchar *) g_bytes_get_data (bytes, &serialised.size);
+   serialised.depth = 0;
+   serialised.ordered_offsets_up_to = trusted ? G_MAXSIZE : 0;
++  serialised.checked_offsets_up_to = trusted ? G_MAXSIZE : 0;
+ 
+   if (!g_variant_serialised_check (serialised))
+     {
+@@ -647,6 +672,7 @@ g_variant_new_from_bytes (const GVariantType *type,
+     }
+ 
+   value->contents.serialised.ordered_offsets_up_to = trusted ? G_MAXSIZE : 0;
++  value->contents.serialised.checked_offsets_up_to = trusted ? G_MAXSIZE : 0;
+ 
+   g_clear_pointer (&owned_bytes, g_bytes_unref);
+ 
+@@ -1144,6 +1170,7 @@ g_variant_get_child_value (GVariant *value,
+ 
+     /* Update the cached ordered_offsets_up_to, since @serialised will be thrown away when this function exits */
+     value->contents.serialised.ordered_offsets_up_to = MAX (value->contents.serialised.ordered_offsets_up_to, serialised.ordered_offsets_up_to);
++    value->contents.serialised.checked_offsets_up_to = MAX (value->contents.serialised.checked_offsets_up_to, serialised.checked_offsets_up_to);
+ 
+     /* Check whether this would cause nesting too deep. If so, return a fake
+      * child. The only situation we expect this to happen in is with a variant,
+@@ -1171,6 +1198,7 @@ g_variant_get_child_value (GVariant *value,
+       g_bytes_ref (value->contents.serialised.bytes);
+     child->contents.serialised.data = s_child.data;
+     child->contents.serialised.ordered_offsets_up_to = s_child.ordered_offsets_up_to;
++    child->contents.serialised.checked_offsets_up_to = s_child.checked_offsets_up_to;
+ 
+     return child;
+   }
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index fda59d6843..591522a2e1 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -122,6 +122,8 @@
+  *
+  * @depth has no restrictions; the depth of a top-level serialized #GVariant is
+  * zero, and it increases for each level of nested child.
++ *
++ * @checked_offsets_up_to is always ≥ @ordered_offsets_up_to
+  */
+ 
+ /* < private >
+@@ -149,6 +151,9 @@ g_variant_serialised_check (GVariantSerialised serialised)
+            !(serialised.size == 0 || serialised.data != NULL))
+     return FALSE;
+ 
++  if (serialised.ordered_offsets_up_to > serialised.checked_offsets_up_to)
++    return FALSE;
++
+   /* Depending on the native alignment requirements of the machine, the
+    * compiler will insert either 3 or 7 padding bytes after the char.
+    * This will result in the sizeof() the struct being 12 or 16.
+@@ -268,6 +273,7 @@ gvs_fixed_sized_maybe_get_child (GVariantSerialised value,
+   g_variant_type_info_ref (value.type_info);
+   value.depth++;
+   value.ordered_offsets_up_to = 0;
++  value.checked_offsets_up_to = 0;
+ 
+   return value;
+ }
+@@ -299,7 +305,7 @@ gvs_fixed_sized_maybe_serialise (GVariantSerialised        value,
+ {
+   if (n_children)
+     {
+-      GVariantSerialised child = { NULL, value.data, value.size, value.depth + 1, 0 };
++      GVariantSerialised child = { NULL, value.data, value.size, value.depth + 1, 0, 0 };
+ 
+       gvs_filler (&child, children[0]);
+     }
+@@ -322,6 +328,7 @@ gvs_fixed_sized_maybe_is_normal (GVariantSerialised value)
+       value.type_info = g_variant_type_info_element (value.type_info);
+       value.depth++;
+       value.ordered_offsets_up_to = 0;
++      value.checked_offsets_up_to = 0;
+ 
+       return g_variant_serialised_is_normal (value);
+     }
+@@ -364,6 +371,7 @@ gvs_variable_sized_maybe_get_child (GVariantSerialised value,
+ 
+   value.depth++;
+   value.ordered_offsets_up_to = 0;
++  value.checked_offsets_up_to = 0;
+ 
+   return value;
+ }
+@@ -394,7 +402,7 @@ gvs_variable_sized_maybe_serialise (GVariantSerialised        value,
+ {
+   if (n_children)
+     {
+-      GVariantSerialised child = { NULL, value.data, value.size - 1, value.depth + 1, 0 };
++      GVariantSerialised child = { NULL, value.data, value.size - 1, value.depth + 1, 0, 0 };
+ 
+       /* write the data for the child.  */
+       gvs_filler (&child, children[0]);
+@@ -415,6 +423,7 @@ gvs_variable_sized_maybe_is_normal (GVariantSerialised value)
+   value.size--;
+   value.depth++;
+   value.ordered_offsets_up_to = 0;
++  value.checked_offsets_up_to = 0;
+ 
+   return g_variant_serialised_is_normal (value);
+ }
+@@ -741,39 +750,46 @@ gvs_variable_sized_array_get_child (GVariantSerialised value,
+ 
+   /* If the requested @index_ is beyond the set of indices whose framing offsets
+    * have been checked, check the remaining offsets to see whether they’re
+-   * normal (in order, no overlapping array elements). */
+-  if (index_ > value.ordered_offsets_up_to)
++   * normal (in order, no overlapping array elements).
++   *
++   * Don’t bother checking if the highest known-good offset is lower than the
++   * highest checked offset, as that means there’s an invalid element at that
++   * index, so there’s no need to check further. */
++  if (index_ > value.checked_offsets_up_to &&
++      value.ordered_offsets_up_to == value.checked_offsets_up_to)
+     {
+       switch (offsets.offset_size)
+         {
+         case 1:
+           {
+             value.ordered_offsets_up_to = find_unordered_guint8 (
+-                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++                offsets.array, value.checked_offsets_up_to, index_ + 1);
+             break;
+           }
+         case 2:
+           {
+             value.ordered_offsets_up_to = find_unordered_guint16 (
+-                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++                offsets.array, value.checked_offsets_up_to, index_ + 1);
+             break;
+           }
+         case 4:
+           {
+             value.ordered_offsets_up_to = find_unordered_guint32 (
+-                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++                offsets.array, value.checked_offsets_up_to, index_ + 1);
+             break;
+           }
+         case 8:
+           {
+             value.ordered_offsets_up_to = find_unordered_guint64 (
+-                offsets.array, value.ordered_offsets_up_to, index_ + 1);
++                offsets.array, value.checked_offsets_up_to, index_ + 1);
+             break;
+           }
+         default:
+           /* gvs_get_offset_size() only returns maximum 8 */
+           g_assert_not_reached ();
+         }
++
++      value.checked_offsets_up_to = index_;
+     }
+ 
+   if (index_ > value.ordered_offsets_up_to)
+@@ -918,6 +934,7 @@ gvs_variable_sized_array_is_normal (GVariantSerialised value)
+ 
+   /* All offsets have now been checked. */
+   value.ordered_offsets_up_to = G_MAXSIZE;
++  value.checked_offsets_up_to = G_MAXSIZE;
+ 
+   return TRUE;
+ }
+@@ -1042,14 +1059,15 @@ gvs_tuple_get_child (GVariantSerialised value,
+    * all the tuple *elements* here, not just all the framing offsets, since
+    * tuples contain a mix of elements which use framing offsets and ones which
+    * don’t. None of them are allowed to overlap. */
+-  if (index_ > value.ordered_offsets_up_to)
++  if (index_ > value.checked_offsets_up_to &&
++      value.ordered_offsets_up_to == value.checked_offsets_up_to)
+     {
+       gsize i, prev_i_end = 0;
+ 
+-      if (value.ordered_offsets_up_to > 0)
+-        gvs_tuple_get_member_bounds (value, value.ordered_offsets_up_to - 1, offset_size, NULL, &prev_i_end);
++      if (value.checked_offsets_up_to > 0)
++        gvs_tuple_get_member_bounds (value, value.checked_offsets_up_to - 1, offset_size, NULL, &prev_i_end);
+ 
+-      for (i = value.ordered_offsets_up_to; i <= index_; i++)
++      for (i = value.checked_offsets_up_to; i <= index_; i++)
+         {
+           gsize i_start, i_end;
+ 
+@@ -1062,6 +1080,7 @@ gvs_tuple_get_child (GVariantSerialised value,
+         }
+ 
+       value.ordered_offsets_up_to = i - 1;
++      value.checked_offsets_up_to = index_;
+     }
+ 
+   if (index_ > value.ordered_offsets_up_to)
+@@ -1259,6 +1278,7 @@ gvs_tuple_is_normal (GVariantSerialised value)
+ 
+   /* All element bounds have been checked above. */
+   value.ordered_offsets_up_to = G_MAXSIZE;
++  value.checked_offsets_up_to = G_MAXSIZE;
+ 
+   {
+     gsize fixed_size;
+diff --git a/glib/gvariant-serialiser.h b/glib/gvariant-serialiser.h
+index 661bd8fd1b..eb74fe7804 100644
+--- a/glib/gvariant-serialiser.h
++++ b/glib/gvariant-serialiser.h
+@@ -43,6 +43,15 @@ typedef struct
+    * Even when dealing with tuples, @ordered_offsets_up_to is an element index,
+    * rather than an index into the frame offsets. */
+   gsize             ordered_offsets_up_to;
++
++  /* Similar to @ordered_offsets_up_to. This gives the index of the child element
++   * whose frame offset is the highest in the offset table which has been
++   * checked so far.
++   *
++   * This is always ≥ @ordered_offsets_up_to. It is always an element index.
++   *
++   * See documentation in gvariant-core.c for `struct GVariant` for details. */
++  gsize             checked_offsets_up_to;
+ } GVariantSerialised;
+ 
+ /* deserialization */
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index 16af7a5678..48e49490ba 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -6011,6 +6011,7 @@ g_variant_byteswap (GVariant *value)
+       serialised.data = g_malloc (serialised.size);
+       serialised.depth = g_variant_get_depth (trusted);
+       serialised.ordered_offsets_up_to = G_MAXSIZE;  /* operating on the normal form */
++      serialised.checked_offsets_up_to = G_MAXSIZE;
+       g_variant_store (trusted, serialised.data);
+       g_variant_unref (trusted);
+ 
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index 0cb69d4b70..941e58f1bc 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -1284,6 +1284,7 @@ random_instance_filler (GVariantSerialised *serialised,
+ 
+   serialised->depth = 0;
+   serialised->ordered_offsets_up_to = 0;
++  serialised->checked_offsets_up_to = 0;
+ 
+   g_assert_true (serialised->type_info == instance->type_info);
+   g_assert_cmpuint (serialised->size, ==, instance->size);
+@@ -1451,6 +1452,7 @@ test_maybe (void)
+         serialised.size = needed_size;
+         serialised.depth = 0;
+         serialised.ordered_offsets_up_to = 0;
++        serialised.checked_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised,
+                                         random_instance_filler,
+@@ -1575,6 +1577,7 @@ test_array (void)
+         serialised.size = needed_size;
+         serialised.depth = 0;
+         serialised.ordered_offsets_up_to = 0;
++        serialised.checked_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised, random_instance_filler,
+                                         (gpointer *) instances, n_children);
+@@ -1740,6 +1743,7 @@ test_tuple (void)
+         serialised.size = needed_size;
+         serialised.depth = 0;
+         serialised.ordered_offsets_up_to = 0;
++        serialised.checked_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised, random_instance_filler,
+                                         (gpointer *) instances, n_children);
+@@ -1837,6 +1841,7 @@ test_variant (void)
+         serialised.size = needed_size;
+         serialised.depth = 0;
+         serialised.ordered_offsets_up_to = 0;
++        serialised.checked_offsets_up_to = 0;
+ 
+         g_variant_serialiser_serialise (serialised, random_instance_filler,
+                                         (gpointer *) &instance, 1);
+-- 
+GitLab
+
+
+From 8c1a7815e7e6695c120cdedff48395c1222af6d1 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <withnall@endlessm.com>
+Date: Fri, 12 Jun 2020 18:01:13 +0100
+Subject: [PATCH 09/18] tests: Add another test for overlapping offsets in
+ GVariant
+
+Signed-off-by: Philip Withnall <withnall@endlessm.com>
+
+Helps: #2121
+---
+ glib/tests/gvariant.c | 34 ++++++++++++++++++++++++++++++++++
+ 1 file changed, 34 insertions(+)
+
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index 941e58f1bc..867cb5b9b4 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -5119,6 +5119,38 @@ test_recursion_limits_array_in_variant (void)
+   g_variant_unref (wrapper_variant);
+ }
+ 
++/* Test that a nested array with invalid values in its offset table (which point
++ * from the inner to the outer array) is normalised successfully without
++ * looping infinitely. */
++static void
++test_normal_checking_array_offsets_overlapped (void)
++{
++  const guint8 data[] = {
++    0x01, 0x00,
++  };
++  gsize size = sizeof (data);
++  GVariant *variant = NULL;
++  GVariant *normal_variant = NULL;
++  GVariant *expected_variant = NULL;
++
++  variant = g_variant_new_from_data (G_VARIANT_TYPE ("aay"), data, size,
++                                     FALSE, NULL, NULL);
++  g_assert_nonnull (variant);
++
++  normal_variant = g_variant_get_normal_form (variant);
++  g_assert_nonnull (normal_variant);
++
++  expected_variant = g_variant_new_parsed ("[@ay [], []]");
++  g_assert_cmpvariant (normal_variant, expected_variant);
++
++  g_assert_cmpmem (g_variant_get_data (normal_variant), g_variant_get_size (normal_variant),
++                   g_variant_get_data (expected_variant), g_variant_get_size (expected_variant));
++
++  g_variant_unref (expected_variant);
++  g_variant_unref (normal_variant);
++  g_variant_unref (variant);
++}
++
+ /* Test that an array with invalidly large values in its offset table is
+  * normalised successfully without looping infinitely. */
+ static void
+@@ -5520,6 +5552,8 @@ main (int argc, char **argv)
+ 
+   g_test_add_func ("/gvariant/normal-checking/tuples",
+                    test_normal_checking_tuples);
++  g_test_add_func ("/gvariant/normal-checking/array-offsets/overlapped",
++                   test_normal_checking_array_offsets_overlapped);
+   g_test_add_func ("/gvariant/normal-checking/array-offsets",
+                    test_normal_checking_array_offsets);
+   g_test_add_func ("/gvariant/normal-checking/array-offsets2",
+-- 
+GitLab
+
+
+From 019505a7ccc32d0afa06e104dc0ac2e63e6f7189 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Mon, 24 Oct 2022 16:43:23 +0100
+Subject: [PATCH 10/18] tests: Disable some random instance tests of GVariants
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Building a `GVariant` using entirely random data may result in a
+non-normally-formed `GVariant`. It’s always possible to read these
+`GVariant`s, but the API might return default values for some or all of
+their components.
+
+In particular, this can easily happen when randomly generating the
+offset tables for non-fixed-width container types.
+
+If it does happen, bytewise comparison of the parsed `GVariant` with the
+original bytes will not always match. So skip those checks.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2121
+---
+ glib/tests/gvariant.c | 12 +++++++++---
+ 1 file changed, 9 insertions(+), 3 deletions(-)
+
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index 867cb5b9b4..9739993e66 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -1231,6 +1231,7 @@ random_instance_assert (RandomInstance *instance,
+   GRand *rand;
+   gsize i;
+ 
++  g_assert_true (size == 0 || buffer != NULL);
+   g_assert_cmpint ((gsize) buffer & ALIGN_BITS & instance->alignment, ==, 0);
+   g_assert_cmpint (size, ==, instance->size);
+ 
+@@ -1457,10 +1458,13 @@ test_maybe (void)
+         g_variant_serialiser_serialise (serialised,
+                                         random_instance_filler,
+                                         (gpointer *) &instance, 1);
++
+         child = g_variant_serialised_get_child (serialised, 0);
+         g_assert_true (child.type_info == instance->type_info);
+-        random_instance_assert (instance, child.data, child.size);
++        if (child.data != NULL)  /* could be NULL if element is non-normal */
++          random_instance_assert (instance, child.data, child.size);
+         g_variant_type_info_unref (child.type_info);
++
+         flavoured_free (serialised.data, flavour);
+       }
+   }
+@@ -1593,7 +1597,8 @@ test_array (void)
+ 
+             child = g_variant_serialised_get_child (serialised, i);
+             g_assert_true (child.type_info == instances[i]->type_info);
+-            random_instance_assert (instances[i], child.data, child.size);
++            if (child.data != NULL)  /* could be NULL if element is non-normal */
++              random_instance_assert (instances[i], child.data, child.size);
+             g_variant_type_info_unref (child.type_info);
+           }
+ 
+@@ -1759,7 +1764,8 @@ test_tuple (void)
+ 
+             child = g_variant_serialised_get_child (serialised, i);
+             g_assert_true (child.type_info == instances[i]->type_info);
+-            random_instance_assert (instances[i], child.data, child.size);
++            if (child.data != NULL)  /* could be NULL if element is non-normal */
++              random_instance_assert (instances[i], child.data, child.size);
+             g_variant_type_info_unref (child.type_info);
+           }
+ 
+-- 
+GitLab
+
+
+From 9d2a142807806212a23436d0332b0209733810f2 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Mon, 24 Oct 2022 18:14:57 +0100
+Subject: [PATCH 11/18] gvariant: Clarify the docs for
+ g_variant_get_normal_form()
+
+Document how non-normal parts of the `GVariant` are handled.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+---
+ glib/gvariant.c | 4 +++-
+ 1 file changed, 3 insertions(+), 1 deletion(-)
+
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index 48e49490ba..e92564eb64 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -5936,7 +5936,9 @@ g_variant_deep_copy (GVariant *value)
+  * marked as trusted and a new reference to it is returned.
+  *
+  * If @value is found not to be in normal form then a new trusted
+- * #GVariant is created with the same value as @value.
++ * #GVariant is created with the same value as @value. The non-normal parts of
++ * @value will be replaced with default values which are guaranteed to be in
++ * normal form.
+  *
+  * It makes sense to call this function if you've received #GVariant
+  * data from untrusted sources and you want to ensure your serialized
+-- 
+GitLab
+
+
+From b0ccb1616688290088e49dea2dc0d7fe723136e4 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Mon, 24 Oct 2022 18:43:55 +0100
+Subject: [PATCH 12/18] gvariant: Port g_variant_deep_copy() to count its
+ iterations directly
+
+This is equivalent to what `GVariantIter` does, but it means that
+`g_variant_deep_copy()` is making its own `g_variant_get_child_value()`
+calls.
+
+This will be useful in an upcoming commit, where those child values will
+be inspected a little more deeply.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2121
+---
+ glib/gvariant.c | 7 +++----
+ 1 file changed, 3 insertions(+), 4 deletions(-)
+
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index e92564eb64..82a921a89e 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -5863,14 +5863,13 @@ g_variant_deep_copy (GVariant *value)
+     case G_VARIANT_CLASS_VARIANT:
+       {
+         GVariantBuilder builder;
+-        GVariantIter iter;
+-        GVariant *child;
++        gsize i, n_children;
+ 
+         g_variant_builder_init (&builder, g_variant_get_type (value));
+-        g_variant_iter_init (&iter, value);
+ 
+-        while ((child = g_variant_iter_next_value (&iter)))
++        for (i = 0, n_children = g_variant_n_children (value); i < n_children; i++)
+           {
++            GVariant *child = g_variant_get_child_value (value, i);
+             g_variant_builder_add_value (&builder, g_variant_deep_copy (child));
+             g_variant_unref (child);
+           }
+-- 
+GitLab
+
+
+From 1770e255ae6cc3f0bf5312322432bbc6524a3632 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Tue, 25 Oct 2022 13:03:22 +0100
+Subject: [PATCH 13/18] gvariant: Add internal
+ g_variant_maybe_get_child_value()
+
+This will be used in a following commit.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2540
+---
+ glib/gvariant-core.c | 68 ++++++++++++++++++++++++++++++++++++++++++++
+ glib/gvariant-core.h |  3 ++
+ 2 files changed, 71 insertions(+)
+
+diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
+index e61242f763..3f4ca0e6dc 100644
+--- a/glib/gvariant-core.c
++++ b/glib/gvariant-core.c
+@@ -1204,6 +1204,74 @@ g_variant_get_child_value (GVariant *value,
+   }
+ }
+ 
++/**
++ * g_variant_maybe_get_child_value:
++ * @value: a container #GVariant
++ * @index_: the index of the child to fetch
++ *
++ * Reads a child item out of a container #GVariant instance, if it is in normal
++ * form. If it is not in normal form, return %NULL.
++ *
++ * This function behaves the same as g_variant_get_child_value(), except that it
++ * returns %NULL if the child is not in normal form. g_variant_get_child_value()
++ * would instead return a new default value of the correct type.
++ *
++ * This is intended to be used internally to avoid unnecessary #GVariant
++ * allocations.
++ *
++ * The returned value is never floating.  You should free it with
++ * g_variant_unref() when you're done with it.
++ *
++ * This function is O(1).
++ *
++ * Returns: (transfer full): the child at the specified index
++ *
++ * Since: 2.74
++ */
++GVariant *
++g_variant_maybe_get_child_value (GVariant *value,
++                                 gsize     index_)
++{
++  g_return_val_if_fail (index_ < g_variant_n_children (value), NULL);
++  g_return_val_if_fail (value->depth < G_MAXSIZE, NULL);
++
++  if (~g_atomic_int_get (&value->state) & STATE_SERIALISED)
++    {
++      g_variant_lock (value);
++
++      if (~value->state & STATE_SERIALISED)
++        {
++          GVariant *child;
++
++          child = g_variant_ref (value->contents.tree.children[index_]);
++          g_variant_unlock (value);
++
++          return child;
++        }
++
++      g_variant_unlock (value);
++    }
++
++  {
++    GVariantSerialised serialised = g_variant_to_serialised (value);
++    GVariantSerialised s_child;
++
++    /* get the serializer to extract the serialized data for the child
++     * from the serialized data for the container
++     */
++    s_child = g_variant_serialised_get_child (serialised, index_);
++
++    if (!(value->state & STATE_TRUSTED) && s_child.data == NULL)
++      {
++        g_variant_type_info_unref (s_child.type_info);
++        return NULL;
++      }
++
++    g_variant_type_info_unref (s_child.type_info);
++    return g_variant_get_child_value (value, index_);
++  }
++}
++
+ /**
+  * g_variant_store:
+  * @value: the #GVariant to store
+diff --git a/glib/gvariant-core.h b/glib/gvariant-core.h
+index a1c34739a3..fb5f4bff45 100644
+--- a/glib/gvariant-core.h
++++ b/glib/gvariant-core.h
+@@ -38,4 +38,7 @@ GVariantTypeInfo *      g_variant_get_type_info                         (GVarian
+ 
+ gsize                   g_variant_get_depth                             (GVariant            *value);
+ 
++GVariant *              g_variant_maybe_get_child_value                 (GVariant            *value,
++                                                                         gsize                index_);
++
+ #endif /* __G_VARIANT_CORE_H__ */
+-- 
+GitLab
+
+
+From 82fc15af4c84a2645343c51b18ab3528c51790ab Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Tue, 25 Oct 2022 13:03:45 +0100
+Subject: [PATCH 14/18] gvariant: Cut allocs of default values for children of
+ non-normal arrays
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This improves a slow case in `g_variant_get_normal_form()` where
+allocating many identical default values for the children of a
+variable-sized array which has a malformed offset table would take a lot
+of time.
+
+The fix is to make all child values after the first invalid one be
+references to the default value emitted for the first invalid one,
+rather than identical new `GVariant`s.
+
+In particular, this fixes a case where an attacker could create an array
+of length L of very large tuples of size T each, corrupt the offset table
+so they don’t have to specify the array content, and then induce
+`g_variant_get_normal_form()` into allocating L×T default values from an
+input which is significantly smaller than L×T in length.
+
+A pre-existing workaround for this issue is for code to call
+`g_variant_is_normal_form()` before calling
+`g_variant_get_normal_form()`, and to skip the latter call if the former
+returns false. This commit improves the behaviour in the case that
+`g_variant_get_normal_form()` is called anyway.
+
+This fix changes the time to run the `fuzz_variant_binary` test on the
+testcase from oss-fuzz#19777 from >60s (before being terminated) with
+2.3GB of memory usage and 580k page faults; to 32s, 8.3MB of memory
+usage and 1500 page faults (as measured by `time -v`).
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Fixes: #2540
+oss-fuzz#19777
+---
+ glib/gvariant.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++-
+ 1 file changed, 65 insertions(+), 1 deletion(-)
+
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index 82a921a89e..bb6be363e0 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -5857,7 +5857,6 @@ g_variant_deep_copy (GVariant *value)
+   switch (g_variant_classify (value))
+     {
+     case G_VARIANT_CLASS_MAYBE:
+-    case G_VARIANT_CLASS_ARRAY:
+     case G_VARIANT_CLASS_TUPLE:
+     case G_VARIANT_CLASS_DICT_ENTRY:
+     case G_VARIANT_CLASS_VARIANT:
+@@ -5877,6 +5876,71 @@ g_variant_deep_copy (GVariant *value)
+         return g_variant_builder_end (&builder);
+       }
+ 
++    case G_VARIANT_CLASS_ARRAY:
++      {
++        GVariantBuilder builder;
++        gsize i, n_children;
++        GVariant *first_invalid_child_deep_copy = NULL;
++
++        /* Arrays are in theory treated the same as maybes, tuples, dict entries
++         * and variants, and could be another case in the above block of code.
++         *
++         * However, they have the property that when dealing with non-normal
++         * data (which is the only time g_variant_deep_copy() is currently
++         * called) in a variable-sized array, the code above can easily end up
++         * creating many default child values in order to return an array which
++         * is of the right length and type, but without containing non-normal
++         * data. This can happen if the offset table for the array is malformed.
++         *
++         * In this case, the code above would end up allocating the same default
++         * value for each one of the child indexes beyond the first malformed
++         * entry in the offset table. This can end up being a lot of identical
++         * allocations of default values, particularly if the non-normal array
++         * is crafted maliciously.
++         *
++         * Avoid that problem by returning a new reference to the same default
++         * value for every child after the first invalid one. This results in
++         * returning an equivalent array, in normal form and trusted — but with
++         * significantly fewer memory allocations.
++         *
++         * See https://gitlab.gnome.org/GNOME/glib/-/issues/2540 */
++
++        g_variant_builder_init (&builder, g_variant_get_type (value));
++
++        for (i = 0, n_children = g_variant_n_children (value); i < n_children; i++)
++          {
++            /* Try maybe_get_child_value() first; if it returns NULL, this child
++             * is non-normal. get_child_value() would have constructed and
++             * returned a default value in that case. */
++            GVariant *child = g_variant_maybe_get_child_value (value, i);
++
++            if (child != NULL)
++              {
++                /* Non-normal children may not always be contiguous, as they may
++                 * be non-normal for reasons other than invalid offset table
++                 * entries. As they are all the same type, they will all have
++                 * the same default value though, so keep that around. */
++                g_variant_builder_add_value (&builder, g_variant_deep_copy (child));
++              }
++            else if (child == NULL && first_invalid_child_deep_copy != NULL)
++              {
++                g_variant_builder_add_value (&builder, first_invalid_child_deep_copy);
++              }
++            else if (child == NULL)
++              {
++                child = g_variant_get_child_value (value, i);
++                first_invalid_child_deep_copy = g_variant_ref_sink (g_variant_deep_copy (child));
++                g_variant_builder_add_value (&builder, first_invalid_child_deep_copy);
++              }
++
++            g_clear_pointer (&child, g_variant_unref);
++          }
++
++        g_clear_pointer (&first_invalid_child_deep_copy, g_variant_unref);
++
++        return g_variant_builder_end (&builder);
++      }
++
+     case G_VARIANT_CLASS_BOOLEAN:
+       return g_variant_new_boolean (g_variant_get_boolean (value));
+ 
+-- 
+GitLab
+
+
+From 935f1c200789c76ad5b51b1f403f611e3cc75318 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Tue, 25 Oct 2022 18:03:56 +0100
+Subject: [PATCH 15/18] gvariant: Fix a leak of a GVariantTypeInfo on an error
+ handling path
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+---
+ glib/gvariant-core.c | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
+index 3f4ca0e6dc..75d23f39af 100644
+--- a/glib/gvariant-core.c
++++ b/glib/gvariant-core.c
+@@ -1183,6 +1183,7 @@ g_variant_get_child_value (GVariant *value,
+         G_VARIANT_MAX_RECURSION_DEPTH - value->depth)
+       {
+         g_assert (g_variant_is_of_type (value, G_VARIANT_TYPE_VARIANT));
++        g_variant_type_info_unref (s_child.type_info);
+         return g_variant_new_tuple (NULL, 0);
+       }
+ 
+-- 
+GitLab
+
+
+From f1dfc5d0c5c0486b5fccb2ceddf1db1162c7033c Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Thu, 27 Oct 2022 12:00:04 +0100
+Subject: [PATCH 16/18] gvariant-serialiser: Check offset table entry size is
+ minimal
+
+The entries in an offset table (which is used for variable sized arrays
+and tuples containing variable sized members) are sized so that they can
+address every byte in the overall variant.
+
+The specification requires that for a variant to be in normal form, its
+offset table entries must be the minimum width such that they can
+address every byte in the variant.
+
+That minimality requirement was not checked in
+`g_variant_is_normal_form()`, leading to two different byte arrays being
+interpreted as the normal form of a given variant tree. That kind of
+confusion could potentially be exploited, and is certainly a bug.
+
+Fix it by adding the necessary checks on offset table entry width, and
+unit tests.
+
+Spotted by William Manley.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Fixes: #2794
+---
+ glib/gvariant-serialiser.c |  19 +++-
+ glib/tests/gvariant.c      | 176 +++++++++++++++++++++++++++++++++++++
+ 2 files changed, 194 insertions(+), 1 deletion(-)
+
+diff --git a/glib/gvariant-serialiser.c b/glib/gvariant-serialiser.c
+index 591522a2e1..25c85b30b1 100644
+--- a/glib/gvariant-serialiser.c
++++ b/glib/gvariant-serialiser.c
+@@ -696,6 +696,10 @@ gvs_variable_sized_array_get_frame_offsets (GVariantSerialised value)
+   out.data_size = last_end;
+   out.array = value.data + last_end;
+   out.length = offsets_array_size / out.offset_size;
++
++  if (out.length > 0 && gvs_calculate_total_size (last_end, out.length) != value.size)
++    return out;  /* offset size not minimal */
++
+   out.is_normal = TRUE;
+ 
+   return out;
+@@ -1203,6 +1207,7 @@ gvs_tuple_is_normal (GVariantSerialised value)
+   gsize length;
+   gsize offset;
+   gsize i;
++  gsize offset_table_size;
+ 
+   /* as per the comment in gvs_tuple_get_child() */
+   if G_UNLIKELY (value.data == NULL && value.size != 0)
+@@ -1307,7 +1312,19 @@ gvs_tuple_is_normal (GVariantSerialised value)
+       }
+   }
+ 
+-  return offset_ptr == offset;
++  /* @offset_ptr has been counting backwards from the end of the variant, to
++   * find the beginning of the offset table. @offset has been counting forwards
++   * from the beginning of the variant to find the end of the data. They should
++   * have met in the middle. */
++  if (offset_ptr != offset)
++    return FALSE;
++
++  offset_table_size = value.size - offset_ptr;
++  if (value.size > 0 &&
++      gvs_calculate_total_size (offset, offset_table_size / offset_size) != value.size)
++    return FALSE;  /* offset size not minimal */
++
++  return TRUE;
+ }
+ 
+ /* Variants {{{2
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index 9739993e66..339edc4e04 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -5222,6 +5222,86 @@ test_normal_checking_array_offsets2 (void)
+   g_variant_unref (variant);
+ }
+ 
++/* Test that an otherwise-valid serialised GVariant is considered non-normal if
++ * its offset table entries are too wide.
++ *
++ * See §2.3.6 (Framing Offsets) of the GVariant specification. */
++static void
++test_normal_checking_array_offsets_minimal_sized (void)
++{
++  GVariantBuilder builder;
++  gsize i;
++  GVariant *aay_constructed = NULL;
++  const guint8 *data = NULL;
++  guint8 *data_owned = NULL;
++  GVariant *aay_deserialised = NULL;
++  GVariant *aay_normalised = NULL;
++
++  /* Construct an array of type aay, consisting of 128 elements which are each
++   * an empty array, i.e. `[[] * 128]`. This is chosen because the inner
++   * elements are variable sized (making the outer array variable sized, so it
++   * must have an offset table), but they are also zero-sized when serialised.
++   * So the serialised representation of @aay_constructed consists entirely of
++   * its offset table, which is entirely zeroes.
++   *
++   * The array is chosen to be 128 elements long because that means offset
++   * table entries which are 1 byte long. If the elements in the array were
++   * non-zero-sized (to the extent that the overall array is ≥256 bytes long),
++   * the offset table entries would end up being 2 bytes long. */
++  g_variant_builder_init (&builder, G_VARIANT_TYPE ("aay"));
++
++  for (i = 0; i < 128; i++)
++    g_variant_builder_add_value (&builder, g_variant_new_array (G_VARIANT_TYPE_BYTE, NULL, 0));
++
++  aay_constructed = g_variant_builder_end (&builder);
++
++  /* Verify that the constructed array is in normal form, and its serialised
++   * form is `b'\0' * 128`. */
++  g_assert_true (g_variant_is_normal_form (aay_constructed));
++  g_assert_cmpuint (g_variant_n_children (aay_constructed), ==, 128);
++  g_assert_cmpuint (g_variant_get_size (aay_constructed), ==, 128);
++
++  data = g_variant_get_data (aay_constructed);
++  for (i = 0; i < g_variant_get_size (aay_constructed); i++)
++    g_assert_cmpuint (data[i], ==, 0);
++
++  /* Construct a serialised `aay` GVariant which is `b'\0' * 256`. This has to
++   * be a non-normal form of `[[] * 128]`, with 2-byte-long offset table
++   * entries, because each offset table entry has to be able to reference all of
++   * the byte boundaries in the container. All the entries in the offset table
++   * are zero, so all the elements of the array are zero-sized. */
++  data = data_owned = g_malloc0 (256);
++  aay_deserialised = g_variant_new_from_data (G_VARIANT_TYPE ("aay"),
++                                              data,
++                                              256,
++                                              FALSE,
++                                              g_free,
++                                              g_steal_pointer (&data_owned));
++
++  g_assert_false (g_variant_is_normal_form (aay_deserialised));
++  g_assert_cmpuint (g_variant_n_children (aay_deserialised), ==, 128);
++  g_assert_cmpuint (g_variant_get_size (aay_deserialised), ==, 256);
++
++  data = g_variant_get_data (aay_deserialised);
++  for (i = 0; i < g_variant_get_size (aay_deserialised); i++)
++    g_assert_cmpuint (data[i], ==, 0);
++
++  /* Get its normal form. That should change the serialised size. */
++  aay_normalised = g_variant_get_normal_form (aay_deserialised);
++
++  g_assert_true (g_variant_is_normal_form (aay_normalised));
++  g_assert_cmpuint (g_variant_n_children (aay_normalised), ==, 128);
++  g_assert_cmpuint (g_variant_get_size (aay_normalised), ==, 128);
++
++  data = g_variant_get_data (aay_normalised);
++  for (i = 0; i < g_variant_get_size (aay_normalised); i++)
++    g_assert_cmpuint (data[i], ==, 0);
++
++  g_variant_unref (aay_normalised);
++  g_variant_unref (aay_deserialised);
++  g_variant_unref (aay_constructed);
++}
++
+ /* Test that a tuple with invalidly large values in its offset table is
+  * normalised successfully without looping infinitely. */
+ static void
+@@ -5416,6 +5496,98 @@ test_normal_checking_tuple_offsets4 (void)
+   g_variant_unref (variant);
+ }
+ 
++/* Test that an otherwise-valid serialised GVariant is considered non-normal if
++ * its offset table entries are too wide.
++ *
++ * See §2.3.6 (Framing Offsets) of the GVariant specification. */
++static void
++test_normal_checking_tuple_offsets_minimal_sized (void)
++{
++  GString *type_string = NULL;
++  GVariantBuilder builder;
++  gsize i;
++  GVariant *ray_constructed = NULL;
++  const guint8 *data = NULL;
++  guint8 *data_owned = NULL;
++  GVariant *ray_deserialised = NULL;
++  GVariant *ray_normalised = NULL;
++
++  /* Construct a tuple of type (ay…ay), consisting of 129 members which are each
++   * an empty array, i.e. `([] * 129)`. This is chosen because the inner
++   * members are variable sized, so the outer tuple must have an offset table,
++   * but they are also zero-sized when serialised. So the serialised
++   * representation of @ray_constructed consists entirely of its offset table,
++   * which is entirely zeroes.
++   *
++   * The tuple is chosen to be 129 members long because that means it has 128
++   * offset table entries which are 1 byte long each. If the members in the
++   * tuple were non-zero-sized (to the extent that the overall tuple is ≥256
++   * bytes long), the offset table entries would end up being 2 bytes long.
++   *
++   * 129 members are used unlike 128 array elements in
++   * test_normal_checking_array_offsets_minimal_sized(), because the last member
++   * in a tuple never needs an offset table entry. */
++  type_string = g_string_new ("");
++  g_string_append_c (type_string, '(');
++  for (i = 0; i < 129; i++)
++    g_string_append (type_string, "ay");
++  g_string_append_c (type_string, ')');
++
++  g_variant_builder_init (&builder, G_VARIANT_TYPE (type_string->str));
++
++  for (i = 0; i < 129; i++)
++    g_variant_builder_add_value (&builder, g_variant_new_array (G_VARIANT_TYPE_BYTE, NULL, 0));
++
++  ray_constructed = g_variant_builder_end (&builder);
++
++  /* Verify that the constructed tuple is in normal form, and its serialised
++   * form is `b'\0' * 128`. */
++  g_assert_true (g_variant_is_normal_form (ray_constructed));
++  g_assert_cmpuint (g_variant_n_children (ray_constructed), ==, 129);
++  g_assert_cmpuint (g_variant_get_size (ray_constructed), ==, 128);
++
++  data = g_variant_get_data (ray_constructed);
++  for (i = 0; i < g_variant_get_size (ray_constructed); i++)
++    g_assert_cmpuint (data[i], ==, 0);
++
++  /* Construct a serialised `(ay…ay)` GVariant which is `b'\0' * 256`. This has
++   * to be a non-normal form of `([] * 129)`, with 2-byte-long offset table
++   * entries, because each offset table entry has to be able to reference all of
++   * the byte boundaries in the container. All the entries in the offset table
++   * are zero, so all the members of the tuple are zero-sized. */
++  data = data_owned = g_malloc0 (256);
++  ray_deserialised = g_variant_new_from_data (G_VARIANT_TYPE (type_string->str),
++                                              data,
++                                              256,
++                                              FALSE,
++                                              g_free,
++                                              g_steal_pointer (&data_owned));
++
++  g_assert_false (g_variant_is_normal_form (ray_deserialised));
++  g_assert_cmpuint (g_variant_n_children (ray_deserialised), ==, 129);
++  g_assert_cmpuint (g_variant_get_size (ray_deserialised), ==, 256);
++
++  data = g_variant_get_data (ray_deserialised);
++  for (i = 0; i < g_variant_get_size (ray_deserialised); i++)
++    g_assert_cmpuint (data[i], ==, 0);
++
++  /* Get its normal form. That should change the serialised size. */
++  ray_normalised = g_variant_get_normal_form (ray_deserialised);
++
++  g_assert_true (g_variant_is_normal_form (ray_normalised));
++  g_assert_cmpuint (g_variant_n_children (ray_normalised), ==, 129);
++  g_assert_cmpuint (g_variant_get_size (ray_normalised), ==, 128);
++
++  data = g_variant_get_data (ray_normalised);
++  for (i = 0; i < g_variant_get_size (ray_normalised); i++)
++    g_assert_cmpuint (data[i], ==, 0);
++
++  g_variant_unref (ray_normalised);
++  g_variant_unref (ray_deserialised);
++  g_variant_unref (ray_constructed);
++  g_string_free (type_string, TRUE);
++}
++
+ /* Test that an empty object path is normalised successfully to the base object
+  * path, ‘/’. */
+ static void
+@@ -5564,6 +5736,8 @@ main (int argc, char **argv)
+                    test_normal_checking_array_offsets);
+   g_test_add_func ("/gvariant/normal-checking/array-offsets2",
+                    test_normal_checking_array_offsets2);
++  g_test_add_func ("/gvariant/normal-checking/array-offsets/minimal-sized",
++                   test_normal_checking_array_offsets_minimal_sized);
+   g_test_add_func ("/gvariant/normal-checking/tuple-offsets",
+                    test_normal_checking_tuple_offsets);
+   g_test_add_func ("/gvariant/normal-checking/tuple-offsets2",
+@@ -5572,6 +5746,8 @@ main (int argc, char **argv)
+                    test_normal_checking_tuple_offsets3);
+   g_test_add_func ("/gvariant/normal-checking/tuple-offsets4",
+                    test_normal_checking_tuple_offsets4);
++  g_test_add_func ("/gvariant/normal-checking/tuple-offsets/minimal-sized",
++                   test_normal_checking_tuple_offsets_minimal_sized);
+   g_test_add_func ("/gvariant/normal-checking/empty-object-path",
+                    test_normal_checking_empty_object_path);
+ 
+-- 
+GitLab
+
+
+From 781f05a22ef11d8a2177b4e9078978decec36dd0 Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Thu, 27 Oct 2022 16:13:54 +0100
+Subject: [PATCH 17/18] gvariant: Fix g_variant_byteswap() returning non-normal
+ data sometimes
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+If `g_variant_byteswap()` was called on a non-normal variant of a type
+which doesn’t need byteswapping, it would return a non-normal output.
+
+That contradicts the documentation, which says that the return value is
+always in normal form.
+
+Fix the code so it matches the documentation.
+
+Includes a unit test.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Helps: #2797
+---
+ glib/gvariant.c       |  8 +++++---
+ glib/tests/gvariant.c | 24 ++++++++++++++++++++++++
+ 2 files changed, 29 insertions(+), 3 deletions(-)
+
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index bb6be363e0..b3495d5cab 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -6083,14 +6083,16 @@ g_variant_byteswap (GVariant *value)
+       g_variant_serialised_byteswap (serialised);
+ 
+       bytes = g_bytes_new_take (serialised.data, serialised.size);
+-      new = g_variant_new_from_bytes (g_variant_get_type (value), bytes, TRUE);
++      new = g_variant_ref_sink (g_variant_new_from_bytes (g_variant_get_type (value), bytes, TRUE));
+       g_bytes_unref (bytes);
+     }
+   else
+     /* contains no multi-byte data */
+-    new = value;
++    new = g_variant_get_normal_form (value);
+ 
+-  return g_variant_ref_sink (new);
++  g_assert (g_variant_is_trusted (new));
++
++  return g_steal_pointer (&new);
+ }
+ 
+ /**
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index 339edc4e04..bea16b5e58 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -3826,6 +3826,29 @@ test_gv_byteswap (void)
+   g_free (string);
+ }
+ 
++static void
++test_gv_byteswap_non_normal_non_aligned (void)
++{
++  const guint8 data[] = { 0x02 };
++  GVariant *v = NULL;
++  GVariant *v_byteswapped = NULL;
++
++  g_test_summary ("Test that calling g_variant_byteswap() on a variant which "
++                  "is in non-normal form and doesn’t need byteswapping returns "
++                  "the same variant in normal form.");
++
++  v = g_variant_new_from_data (G_VARIANT_TYPE_BOOLEAN, data, sizeof (data), FALSE, NULL, NULL);
++  g_assert_false (g_variant_is_normal_form (v));
++
++  v_byteswapped = g_variant_byteswap (v);
++  g_assert_true (g_variant_is_normal_form (v_byteswapped));
++
++  g_assert_cmpvariant (v, v_byteswapped);
++
++  g_variant_unref (v);
++  g_variant_unref (v_byteswapped);
++}
++
+ static void
+ test_parser (void)
+ {
+@@ -5699,6 +5722,7 @@ main (int argc, char **argv)
+   g_test_add_func ("/gvariant/builder-memory", test_builder_memory);
+   g_test_add_func ("/gvariant/hashing", test_hashing);
+   g_test_add_func ("/gvariant/byteswap", test_gv_byteswap);
++  g_test_add_func ("/gvariant/byteswap/non-normal-non-aligned", test_gv_byteswap_non_normal_non_aligned);
+   g_test_add_func ("/gvariant/parser", test_parses);
+   g_test_add_func ("/gvariant/parser/integer-bounds", test_parser_integer_bounds);
+   g_test_add_func ("/gvariant/parser/recursion", test_parser_recursion);
+-- 
+GitLab
+
+
+From 7d7efce1d9c379fdd7d2ff58caea88f8806fdd2e Mon Sep 17 00:00:00 2001
+From: Philip Withnall <pwithnall@endlessos.org>
+Date: Thu, 27 Oct 2022 22:53:13 +0100
+Subject: [PATCH 18/18] gvariant: Allow g_variant_byteswap() to operate on
+ tree-form variants
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This avoids needing to always serialise a variant before byteswapping it.
+With variants in non-normal forms, serialisation can result in a large
+increase in size of the variant, and a lot of allocations for leaf
+`GVariant`s. This can lead to a denial of service attack.
+
+Avoid that by changing byteswapping so that it happens on the tree form
+of the variant if the input is in non-normal form. If the input is in
+normal form (either serialised or in tree form), continue using the
+existing code as byteswapping an already-serialised normal variant is
+about 3× faster than byteswapping on the equivalent tree form.
+
+The existing unit tests cover byteswapping well, but need some
+adaptation so that they operate on tree form variants too.
+
+I considered dropping the serialised byteswapping code and doing all
+byteswapping on tree-form variants, as that would make maintenance
+simpler (avoiding having two parallel implementations of byteswapping).
+However, most inputs to `g_variant_byteswap()` are likely to be
+serialised variants (coming from a byte array of input from some foreign
+source) and most of them are going to be in normal form (as corruption
+and malicious action are rare). So getting rid of the serialised
+byteswapping code would impose quite a performance penalty on the common
+case.
+
+Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
+
+Fixes: #2797
+---
+ glib/gvariant.c       | 87 ++++++++++++++++++++++++++++++++-----------
+ glib/tests/gvariant.c | 57 ++++++++++++++++++++++++----
+ 2 files changed, 115 insertions(+), 29 deletions(-)
+
+diff --git a/glib/gvariant.c b/glib/gvariant.c
+index b3495d5cab..95904bd382 100644
+--- a/glib/gvariant.c
++++ b/glib/gvariant.c
+@@ -5852,7 +5852,8 @@ g_variant_iter_loop (GVariantIter *iter,
+ 
+ /* Serialized data {{{1 */
+ static GVariant *
+-g_variant_deep_copy (GVariant *value)
++g_variant_deep_copy (GVariant *value,
++                     gboolean  byteswap)
+ {
+   switch (g_variant_classify (value))
+     {
+@@ -5869,7 +5870,7 @@ g_variant_deep_copy (GVariant *value)
+         for (i = 0, n_children = g_variant_n_children (value); i < n_children; i++)
+           {
+             GVariant *child = g_variant_get_child_value (value, i);
+-            g_variant_builder_add_value (&builder, g_variant_deep_copy (child));
++            g_variant_builder_add_value (&builder, g_variant_deep_copy (child, byteswap));
+             g_variant_unref (child);
+           }
+ 
+@@ -5920,7 +5921,7 @@ g_variant_deep_copy (GVariant *value)
+                  * be non-normal for reasons other than invalid offset table
+                  * entries. As they are all the same type, they will all have
+                  * the same default value though, so keep that around. */
+-                g_variant_builder_add_value (&builder, g_variant_deep_copy (child));
++                g_variant_builder_add_value (&builder, g_variant_deep_copy (child, byteswap));
+               }
+             else if (child == NULL && first_invalid_child_deep_copy != NULL)
+               {
+@@ -5929,7 +5930,7 @@ g_variant_deep_copy (GVariant *value)
+             else if (child == NULL)
+               {
+                 child = g_variant_get_child_value (value, i);
+-                first_invalid_child_deep_copy = g_variant_ref_sink (g_variant_deep_copy (child));
++                first_invalid_child_deep_copy = g_variant_ref_sink (g_variant_deep_copy (child, byteswap));
+                 g_variant_builder_add_value (&builder, first_invalid_child_deep_copy);
+               }
+ 
+@@ -5948,28 +5949,63 @@ g_variant_deep_copy (GVariant *value)
+       return g_variant_new_byte (g_variant_get_byte (value));
+ 
+     case G_VARIANT_CLASS_INT16:
+-      return g_variant_new_int16 (g_variant_get_int16 (value));
++      if (byteswap)
++        return g_variant_new_int16 (GUINT16_SWAP_LE_BE (g_variant_get_int16 (value)));
++      else
++        return g_variant_new_int16 (g_variant_get_int16 (value));
+ 
+     case G_VARIANT_CLASS_UINT16:
+-      return g_variant_new_uint16 (g_variant_get_uint16 (value));
++      if (byteswap)
++        return g_variant_new_uint16 (GUINT16_SWAP_LE_BE (g_variant_get_uint16 (value)));
++      else
++        return g_variant_new_uint16 (g_variant_get_uint16 (value));
+ 
+     case G_VARIANT_CLASS_INT32:
+-      return g_variant_new_int32 (g_variant_get_int32 (value));
++      if (byteswap)
++        return g_variant_new_int32 (GUINT32_SWAP_LE_BE (g_variant_get_int32 (value)));
++      else
++        return g_variant_new_int32 (g_variant_get_int32 (value));
+ 
+     case G_VARIANT_CLASS_UINT32:
+-      return g_variant_new_uint32 (g_variant_get_uint32 (value));
++      if (byteswap)
++        return g_variant_new_uint32 (GUINT32_SWAP_LE_BE (g_variant_get_uint32 (value)));
++      else
++        return g_variant_new_uint32 (g_variant_get_uint32 (value));
+ 
+     case G_VARIANT_CLASS_INT64:
+-      return g_variant_new_int64 (g_variant_get_int64 (value));
++      if (byteswap)
++        return g_variant_new_int64 (GUINT64_SWAP_LE_BE (g_variant_get_int64 (value)));
++      else
++        return g_variant_new_int64 (g_variant_get_int64 (value));
+ 
+     case G_VARIANT_CLASS_UINT64:
+-      return g_variant_new_uint64 (g_variant_get_uint64 (value));
++      if (byteswap)
++        return g_variant_new_uint64 (GUINT64_SWAP_LE_BE (g_variant_get_uint64 (value)));
++      else
++        return g_variant_new_uint64 (g_variant_get_uint64 (value));
+ 
+     case G_VARIANT_CLASS_HANDLE:
+-      return g_variant_new_handle (g_variant_get_handle (value));
++      if (byteswap)
++        return g_variant_new_handle (GUINT32_SWAP_LE_BE (g_variant_get_handle (value)));
++      else
++        return g_variant_new_handle (g_variant_get_handle (value));
+ 
+     case G_VARIANT_CLASS_DOUBLE:
+-      return g_variant_new_double (g_variant_get_double (value));
++      if (byteswap)
++        {
++          /* We have to convert the double to a uint64 here using a union,
++           * because a cast will round it numerically. */
++          union
++            {
++              guint64 u64;
++              gdouble dbl;
++            } u1, u2;
++          u1.dbl = g_variant_get_double (value);
++          u2.u64 = GUINT64_SWAP_LE_BE (u1.u64);
++          return g_variant_new_double (u2.dbl);
++        }
++      else
++        return g_variant_new_double (g_variant_get_double (value));
+ 
+     case G_VARIANT_CLASS_STRING:
+       return g_variant_new_string (g_variant_get_string (value, NULL));
+@@ -6026,7 +6062,7 @@ g_variant_get_normal_form (GVariant *value)
+   if (g_variant_is_normal_form (value))
+     return g_variant_ref (value);
+ 
+-  trusted = g_variant_deep_copy (value);
++  trusted = g_variant_deep_copy (value, FALSE);
+   g_assert (g_variant_is_trusted (trusted));
+ 
+   return g_variant_ref_sink (trusted);
+@@ -6046,6 +6082,11 @@ g_variant_get_normal_form (GVariant *value)
+  * contain multi-byte numeric data.  That include strings, booleans,
+  * bytes and containers containing only these things (recursively).
+  *
++ * While this function can safely handle untrusted, non-normal data, it is
++ * recommended to check whether the input is in normal form beforehand, using
++ * g_variant_is_normal_form(), and to reject non-normal inputs if your
++ * application can be strict about what inputs it rejects.
++ *
+  * The returned value is always in normal form and is marked as trusted.
+  *
+  * Returns: (transfer full): the byteswapped form of @value
+@@ -6063,22 +6104,21 @@ g_variant_byteswap (GVariant *value)
+ 
+   g_variant_type_info_query (type_info, &alignment, NULL);
+ 
+-  if (alignment)
+-    /* (potentially) contains multi-byte numeric data */
++  if (alignment && g_variant_is_normal_form (value))
+     {
++      /* (potentially) contains multi-byte numeric data, but is also already in
++       * normal form so we can use a faster byteswapping codepath on the
++       * serialised data */
+       GVariantSerialised serialised = { 0, };
+-      GVariant *trusted;
+       GBytes *bytes;
+ 
+-      trusted = g_variant_get_normal_form (value);
+-      serialised.type_info = g_variant_get_type_info (trusted);
+-      serialised.size = g_variant_get_size (trusted);
++      serialised.type_info = g_variant_get_type_info (value);
++      serialised.size = g_variant_get_size (value);
+       serialised.data = g_malloc (serialised.size);
+-      serialised.depth = g_variant_get_depth (trusted);
++      serialised.depth = g_variant_get_depth (value);
+       serialised.ordered_offsets_up_to = G_MAXSIZE;  /* operating on the normal form */
+       serialised.checked_offsets_up_to = G_MAXSIZE;
+-      g_variant_store (trusted, serialised.data);
+-      g_variant_unref (trusted);
++      g_variant_store (value, serialised.data);
+ 
+       g_variant_serialised_byteswap (serialised);
+ 
+@@ -6086,6 +6126,9 @@ g_variant_byteswap (GVariant *value)
+       new = g_variant_ref_sink (g_variant_new_from_bytes (g_variant_get_type (value), bytes, TRUE));
+       g_bytes_unref (bytes);
+     }
++  else if (alignment)
++    /* (potentially) contains multi-byte numeric data */
++    new = g_variant_ref_sink (g_variant_deep_copy (value, TRUE));
+   else
+     /* contains no multi-byte data */
+     new = g_variant_get_normal_form (value);
+diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
+index bea16b5e58..ba837af48d 100644
+--- a/glib/tests/gvariant.c
++++ b/glib/tests/gvariant.c
+@@ -2288,24 +2288,67 @@ serialise_tree (TreeInstance       *tree,
+ static void
+ test_byteswap (void)
+ {
+-  GVariantSerialised one = { 0, }, two = { 0, };
++  GVariantSerialised one = { 0, }, two = { 0, }, three = { 0, };
+   TreeInstance *tree;
+-
++  GVariant *one_variant = NULL;
++  GVariant *two_variant = NULL;
++  GVariant *two_byteswapped = NULL;
++  GVariant *three_variant = NULL;
++  GVariant *three_byteswapped = NULL;
++  guint8 *three_data_copy = NULL;
++  gsize three_size_copy = 0;
++
++  /* Write a tree out twice, once normally and once byteswapped. */
+   tree = tree_instance_new (NULL, 3);
+   serialise_tree (tree, &one);
+ 
++  one_variant = g_variant_new_from_data (G_VARIANT_TYPE (g_variant_type_info_get_type_string (one.type_info)),
++                                         one.data, one.size, FALSE, NULL, NULL);
++
+   i_am_writing_byteswapped = TRUE;
+   serialise_tree (tree, &two);
++  serialise_tree (tree, &three);
+   i_am_writing_byteswapped = FALSE;
+ 
+-  g_variant_serialised_byteswap (two);
+-
+-  g_assert_cmpmem (one.data, one.size, two.data, two.size);
+-  g_assert_cmpuint (one.depth, ==, two.depth);
+-
++  /* Swap the first byteswapped one back using the function we want to test. */
++  two_variant = g_variant_new_from_data (G_VARIANT_TYPE (g_variant_type_info_get_type_string (two.type_info)),
++                                         two.data, two.size, FALSE, NULL, NULL);
++  two_byteswapped = g_variant_byteswap (two_variant);
++
++  /* Make the second byteswapped one non-normal (hopefully), and then byteswap
++   * it back using the function we want to test in its non-normal mode.
++   * This might not work because it’s not necessarily possible to make an
++   * arbitrary random variant non-normal. Adding a single zero byte to the end
++   * often makes something non-normal but still readable. */
++  three_size_copy = three.size + 1;
++  three_data_copy = g_malloc (three_size_copy);
++  memcpy (three_data_copy, three.data, three.size);
++  three_data_copy[three.size] = '\0';
++
++  three_variant = g_variant_new_from_data (G_VARIANT_TYPE (g_variant_type_info_get_type_string (three.type_info)),
++                                           three_data_copy, three_size_copy, FALSE, NULL, NULL);
++  three_byteswapped = g_variant_byteswap (three_variant);
++
++  /* Check they’re the same. We can always compare @one_variant and
++   * @two_byteswapped. We can only compare @two_byteswapped and
++   * @three_byteswapped if @two_variant and @three_variant are equal: in that
++   * case, the corruption to @three_variant was enough to make it non-normal but
++   * not enough to change its value. */
++  g_assert_cmpvariant (one_variant, two_byteswapped);
++
++  if (g_variant_equal (two_variant, three_variant))
++    g_assert_cmpvariant (two_byteswapped, three_byteswapped);
++
++  g_variant_unref (three_byteswapped);
++  g_variant_unref (three_variant);
++  g_variant_unref (two_byteswapped);
++  g_variant_unref (two_variant);
++  g_variant_unref (one_variant);
+   tree_instance_free (tree);
+   g_free (one.data);
+   g_free (two.data);
++  g_free (three.data);
++  g_free (three_data_copy);
+ }
+ 
+ static void
+-- 
+GitLab
+
+
diff --git a/dev-util/glib-utils/glib-utils-2.68.3-r1.ebuild b/dev-util/glib-utils/glib-utils-2.68.3-r2.ebuild
similarity index 100%
rename from dev-util/glib-utils/glib-utils-2.68.3-r1.ebuild
rename to dev-util/glib-utils/glib-utils-2.68.3-r2.ebuild
diff --git a/dev-util/glib-utils/glib-utils-2.68.3.ebuild b/dev-util/glib-utils/glib-utils-2.68.3.ebuild
index 03b0ab5..1bba684 100644
--- a/dev-util/glib-utils/glib-utils-2.68.3.ebuild
+++ b/dev-util/glib-utils/glib-utils-2.68.3.ebuild
@@ -26,6 +26,11 @@
 	cros-host? ( ${BDEPEND} )
 "
 
+PATCHES=(
+       "${FILESDIR}"/glib-2.74.1-normal-form-handling-gvariant.patch
+       "${FILESDIR}"/glib-2.74.1-normal-form-handling-gvariant-patch-fixes.patch
+)
+
 src_configure() { :; }
 
 do_xsltproc_command() {