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authorAndrey Konovalov <andreyknvl@google.com>2021-02-24 12:05:38 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-24 13:38:31 -0800
commit1b1df4c4e2576f6b9c5b1f5f1fc9435e3f6c6b47 (patch)
tree3c91c58eec459fff2f721d662592235b84202213
parent2e4bde6a1e3a3feb8511685b8c97be668728eefb (diff)
kasan: adapt kmalloc_uaf2 test to HW_TAGS mode
In the kmalloc_uaf2() test, the pointers to the two allocated memory blocks might happen to be the same, and the test will fail. With the software tag-based mode, the probability of the that is 1/254, so it's hard to observe the failure. For the hardware tag-based mode though, the probablity is 1/14, which is quite noticable. Allow up to 16 attempts at generating different tags for the tag-based modes. Link: https://linux-review.googlesource.com/id/Ibfa458ef2804ff465d8eb07434a300bf36388d55 Link: https://lkml.kernel.org/r/9cd5cf2f633dcbf55cab801cd26845d2b075cec7.1610733117.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Marco Elver <elver@google.com> Reviewed-by: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Branislav Rankov <Branislav.Rankov@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Evgenii Stepanov <eugenis@google.com> Cc: Kevin Brodsky <kevin.brodsky@arm.com> Cc: Peter Collingbourne <pcc@google.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--lib/test_kasan.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 603fd7937b94..9a227d7e06d6 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -382,7 +382,9 @@ static void kmalloc_uaf2(struct kunit *test)
{
char *ptr1, *ptr2;
size_t size = 43;
+ int counter = 0;
+again:
ptr1 = kmalloc(size, GFP_KERNEL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1);
@@ -391,6 +393,15 @@ static void kmalloc_uaf2(struct kunit *test)
ptr2 = kmalloc(size, GFP_KERNEL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2);
+ /*
+ * For tag-based KASAN ptr1 and ptr2 tags might happen to be the same.
+ * Allow up to 16 attempts at generating different tags.
+ */
+ if (!IS_ENABLED(CONFIG_KASAN_GENERIC) && ptr1 == ptr2 && counter++ < 16) {
+ kfree(ptr2);
+ goto again;
+ }
+
KUNIT_EXPECT_KASAN_FAIL(test, ptr1[40] = 'x');
KUNIT_EXPECT_PTR_NE(test, ptr1, ptr2);