maple_tree: fix allocation in mas_sparse_area()
commit 29ad6bb313487370f9dfe5441fc8982593b6384e upstream.
In the case of reverse allocation, mas->index and mas->last do not point
to the correct allocation range, which will cause users to get incorrect
allocation results, so fix it. If the user does not use it in a specific
way, this bug will not be triggered.
This is a bug, but only VMA uses it now, the way VMA is used now will
not trigger it. There is a possibility that a user will trigger it in
the future.
Also re-check whether the size is still satisfied after the lower bound
was increased, which is a corner case and is incorrect in previous
versions.
BUG=b/346513880
TEST=presubmit
RELEASE_NOTE=None
cos-patch: security-moderate
Link: https://lkml.kernel.org/r/20230419093625.99201-1-zhangpeng.00@bytedance.com
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Change-Id: I82eae1b133e12539195a6281810054f8b937178e
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shuo Yang <gshuoy@google.com>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/76504
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Kevin Berry <kpberry@google.com>
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 4976522..06a9781 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -5277,25 +5277,28 @@ static inline void mas_fill_gap(struct ma_state *mas, void *entry,
* @size: The size of the gap
* @fwd: Searching forward or back
*/
-static inline void mas_sparse_area(struct ma_state *mas, unsigned long min,
+static inline int mas_sparse_area(struct ma_state *mas, unsigned long min,
unsigned long max, unsigned long size, bool fwd)
{
- unsigned long start = 0;
-
- if (!unlikely(mas_is_none(mas)))
- start++;
+ if (!unlikely(mas_is_none(mas)) && min == 0) {
+ min++;
+ /*
+ * At this time, min is increased, we need to recheck whether
+ * the size is satisfied.
+ */
+ if (min > max || max - min + 1 < size)
+ return -EBUSY;
+ }
/* mas_is_ptr */
- if (start < min)
- start = min;
-
if (fwd) {
- mas->index = start;
- mas->last = start + size - 1;
- return;
+ mas->index = min;
+ mas->last = min + size - 1;
+ } else {
+ mas->last = max;
+ mas->index = max - size + 1;
}
-
- mas->index = max;
+ return 0;
}
/*
@@ -5324,10 +5327,8 @@ int mas_empty_area(struct ma_state *mas, unsigned long min,
return -EBUSY;
/* Empty set */
- if (mas_is_none(mas) || mas_is_ptr(mas)) {
- mas_sparse_area(mas, min, max, size, true);
- return 0;
- }
+ if (mas_is_none(mas) || mas_is_ptr(mas))
+ return mas_sparse_area(mas, min, max, size, true);
/* The start of the window can only be within these values */
mas->index = min;
@@ -5377,10 +5378,8 @@ int mas_empty_area_rev(struct ma_state *mas, unsigned long min,
}
/* Empty set. */
- if (mas_is_none(mas) || mas_is_ptr(mas)) {
- mas_sparse_area(mas, min, max, size, false);
- return 0;
- }
+ if (mas_is_none(mas) || mas_is_ptr(mas))
+ return mas_sparse_area(mas, min, max, size, false);
/* The start of the window can only be within these values. */
mas->index = min;
