[PATCH v4 09/15] kasan: adapt kmalloc_uaf2 test to HW_TAGS mode
From: Andrey Konovalov <hidden>
Date: 2021-01-15 17:55:00
Also in:
linux-mm, lkml
Subsystem:
library code, the rest · Maintainers:
Andrew Morton, Linus Torvalds
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 Reviewed-by: Marco Elver <elver@google.com> Reviewed-by: Alexander Potapenko <glider@google.com> Signed-off-by: Andrey Konovalov <redacted> --- lib/test_kasan.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 2419e36e117b..0cda4a1ff394 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);
--
2.30.0.284.gd98b1dd5eaa7-goog
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel