ida: Fix crash in ida_free when the bitmap is empty
[ Upstream commit af73483f4e8b6f5c68c9aa63257bdd929a9c194a ]
The IDA usually detects double-frees, but that detection failed to
consider the case when there are no nearby IDs allocated and so we have a
NULL bitmap rather than simply having a clear bit. Add some tests to the
test-suite to be sure we don't inadvertently reintroduce this problem.
Unfortunately they're quite noisy so include a message to disregard
the warnings.
BUG=b/321923134
TEST=None
RELEASE_NOTE=Fixed CVE-2023-6915 in the linux kernel.
cos-patch: security-high
Reported-by: Zhenghan Wang <wzhmmmmm@gmail.com>
Change-Id: I79ae1d6880159712099af2b541b3909f5244b2b3
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/64331
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Oleksandr Tymoshenko <ovt@google.com>
diff --git a/lib/idr.c b/lib/idr.c
index 13f2758..da36054 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -508,7 +508,7 @@
goto delete;
xas_store(&xas, xa_mk_value(v));
} else {
- if (!test_bit(bit, bitmap->bitmap))
+ if (!bitmap || !test_bit(bit, bitmap->bitmap))
goto err;
__clear_bit(bit, bitmap->bitmap);
xas_set_mark(&xas, XA_FREE_MARK);
diff --git a/lib/test_ida.c b/lib/test_ida.c
index b068806..55105ba 100644
--- a/lib/test_ida.c
+++ b/lib/test_ida.c
@@ -150,6 +150,45 @@
IDA_BUG_ON(ida, !ida_is_empty(ida));
}
+/*
+ * Check various situations where we attempt to free an ID we don't own.
+ */
+static void ida_check_bad_free(struct ida *ida)
+{
+ unsigned long i;
+
+ printk("vvv Ignore \"not allocated\" warnings\n");
+ /* IDA is empty; all of these will fail */
+ ida_free(ida, 0);
+ for (i = 0; i < 31; i++)
+ ida_free(ida, 1 << i);
+
+ /* IDA contains a single value entry */
+ IDA_BUG_ON(ida, ida_alloc_min(ida, 3, GFP_KERNEL) != 3);
+ ida_free(ida, 0);
+ for (i = 0; i < 31; i++)
+ ida_free(ida, 1 << i);
+
+ /* IDA contains a single bitmap */
+ IDA_BUG_ON(ida, ida_alloc_min(ida, 1023, GFP_KERNEL) != 1023);
+ ida_free(ida, 0);
+ for (i = 0; i < 31; i++)
+ ida_free(ida, 1 << i);
+
+ /* IDA contains a tree */
+ IDA_BUG_ON(ida, ida_alloc_min(ida, (1 << 20) - 1, GFP_KERNEL) != (1 << 20) - 1);
+ ida_free(ida, 0);
+ for (i = 0; i < 31; i++)
+ ida_free(ida, 1 << i);
+ printk("^^^ \"not allocated\" warnings over\n");
+
+ ida_free(ida, 3);
+ ida_free(ida, 1023);
+ ida_free(ida, (1 << 20) - 1);
+
+ IDA_BUG_ON(ida, !ida_is_empty(ida));
+}
+
static DEFINE_IDA(ida);
static int ida_checks(void)
@@ -162,6 +201,7 @@
ida_check_leaf(&ida, 1024 * 64);
ida_check_max(&ida);
ida_check_conv(&ida);
+ ida_check_bad_free(&ida);
printk("IDA: %u of %u tests passed\n", tests_passed, tests_run);
return (tests_run != tests_passed) ? 0 : -EINVAL;
