Re: [PATCH 09/11] kasan: fix memory corruption in kasan_bitops_tags test
From: Alexander Potapenko <glider@google.com>
Date: 2021-01-13 12:31:33
Also in:
linux-mm, lkml
On Tue, Jan 12, 2021 at 9:07 PM 'Andrey Konovalov' via kasan-dev [off-list ref] wrote:
On Tue, Jan 12, 2021 at 9:30 AM Alexander Potapenko [off-list ref] wrote:quoted
On Tue, Jan 5, 2021 at 7:28 PM Andrey Konovalov [off-list ref] wrote:quoted
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. Signed-off-by: Andrey Konovalov <redacted> Link: https://linux-review.googlesource.com/id/I67f51d1ee48f0a8d0fe2658c2a39e4879fe0832a
Reviewed-by: Alexander Potapenko <glider@google.com>
quoted
quoted
--- lib/test_kasan.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)diff --git a/lib/test_kasan.c b/lib/test_kasan.c index b67da7f6e17f..3ea52da52714 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c@@ -771,17 +771,17 @@ static void kasan_bitops_tags(struct kunit *test) /* This test is specifically crafted for the tag-based mode. */ if (IS_ENABLED(CONFIG_KASAN_GENERIC)) { - kunit_info(test, "skipping, CONFIG_KASAN_SW_TAGS required"); + kunit_info(test, "skipping, CONFIG_KASAN_SW/HW_TAGS required"); return; } - /* 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);I think it might make sense to call ksize() here to ensure we have these spare bytes.Calling ksize() will unpoison the whole object.
Ah, that's right.
I think it's OK to make assumptions about KASAN internals in tests. I would actually say that we need more tests that check such internal properties.
Agreed. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel