In the kmalloc_uaf2() test, the pointers to the two allocated memory blocks might be the same, and the test will fail. With the software tag-based mode, the probability of the that happening 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 4 attempts at generating different tags for the tag-based modes. Signed-off-by: Andrey Konovalov <andreyk...@google.com> Link: https://linux-review.googlesource.com/id/Ibfa458ef2804ff465d8eb07434a300bf36388d55 --- lib/test_kasan.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/lib/test_kasan.c b/lib/test_kasan.c index b5077a47b95a..b67da7f6e17f 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -375,7 +375,9 @@ 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); @@ -384,6 +386,13 @@ 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 4 attempts at generating different tags. + */ + if (!IS_ENABLED(CONFIG_KASAN_GENERIC) && ptr1 == ptr2 && counter++ < 4) + goto again; + KUNIT_EXPECT_KASAN_FAIL(test, ptr1[40] = 'x'); KUNIT_EXPECT_PTR_NE(test, ptr1, ptr2); -- 2.29.2.729.g45daf8777d-goog
