[PATCH v4 10/15] kasan: fix memory corruption in kasan_bitops_tags test
From: Andrey Konovalov <hidden>
Date: 2021-01-15 17:54:41
Also in:
linux-arm-kernel, lkml
Subsystem:
library code, the rest · Maintainers:
Andrew Morton, Linus Torvalds
Since the hardware tag-based KASAN mode might not have a redzone that comes after an allocated object (when kasan.mode=prod is enabled), the kasan_bitops_tags() test ends up corrupting the next object in memory. Change the test so it always accesses the redzone that lies within the allocated object's boundaries. Link: https://linux-review.googlesource.com/id/I67f51d1ee48f0a8d0fe2658c2a39e4879fe0832a Reviewed-by: Marco Elver <elver@google.com> Reviewed-by: Alexander Potapenko <glider@google.com> Signed-off-by: Andrey Konovalov <redacted> --- lib/test_kasan.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 0cda4a1ff394..a06e7946f581 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c@@ -749,13 +749,13 @@ static void kasan_bitops_tags(struct kunit *test) /* This test is specifically crafted for tag-based modes. */ KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_KASAN_GENERIC); - /* Allocation size will be rounded to up granule size, which is 16. */ - bits = kzalloc(sizeof(*bits), GFP_KERNEL); + /* kmalloc-64 cache will be used and the last 16 bytes will be the redzone. */ + bits = kzalloc(48, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, bits); - /* Do the accesses past the 16 allocated bytes. */ - kasan_bitops_modify(test, BITS_PER_LONG, &bits[1]); - kasan_bitops_test_and_modify(test, BITS_PER_LONG + BITS_PER_BYTE, &bits[1]); + /* Do the accesses past the 48 allocated bytes, but within the redone. */ + kasan_bitops_modify(test, BITS_PER_LONG, (void *)bits + 48); + kasan_bitops_test_and_modify(test, BITS_PER_LONG + BITS_PER_BYTE, (void *)bits + 48); kfree(bits); }
--
2.30.0.284.gd98b1dd5eaa7-goog