Messages in this thread Patch in this message | | | From | Kees Cook <> | Subject | [PATCH] kasan: test: Bypass __alloc_size checks | Date | Tue, 5 Oct 2021 20:55:22 -0700 |
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Intentional overflows, as performed by the KASAN tests, are detected at compile time[1] (instead of only at run-time) with the addition of __alloc_size. Fix this by forcing the compiler into not being able to trust the size used following the kmalloc()s.
[1] https://lore.kernel.org/lkml/20211005184717.65c6d8eb39350395e387b71f@linux-foundation.org
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: kasan-dev@googlegroups.com Signed-off-by: Kees Cook <keescook@chromium.org> --- lib/test_kasan.c | 10 +++++----- lib/test_kasan_module.c | 2 +- 2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 8835e0784578..0e1f8d5281b4 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -435,7 +435,7 @@ static void kmalloc_uaf_16(struct kunit *test) static void kmalloc_oob_memset_2(struct kunit *test) { char *ptr; - size_t size = 128 - KASAN_GRANULE_SIZE; + volatile size_t size = 128 - KASAN_GRANULE_SIZE; ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); @@ -447,7 +447,7 @@ static void kmalloc_oob_memset_2(struct kunit *test) static void kmalloc_oob_memset_4(struct kunit *test) { char *ptr; - size_t size = 128 - KASAN_GRANULE_SIZE; + volatile size_t size = 128 - KASAN_GRANULE_SIZE; ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); @@ -459,7 +459,7 @@ static void kmalloc_oob_memset_4(struct kunit *test) static void kmalloc_oob_memset_8(struct kunit *test) { char *ptr; - size_t size = 128 - KASAN_GRANULE_SIZE; + volatile size_t size = 128 - KASAN_GRANULE_SIZE; ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); @@ -471,7 +471,7 @@ static void kmalloc_oob_memset_8(struct kunit *test) static void kmalloc_oob_memset_16(struct kunit *test) { char *ptr; - size_t size = 128 - KASAN_GRANULE_SIZE; + volatile size_t size = 128 - KASAN_GRANULE_SIZE; ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); @@ -483,7 +483,7 @@ static void kmalloc_oob_memset_16(struct kunit *test) static void kmalloc_oob_in_memset(struct kunit *test) { char *ptr; - size_t size = 128 - KASAN_GRANULE_SIZE; + volatile size_t size = 128 - KASAN_GRANULE_SIZE; ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); diff --git a/lib/test_kasan_module.c b/lib/test_kasan_module.c index 7ebf433edef3..c8cc77b1dcf3 100644 --- a/lib/test_kasan_module.c +++ b/lib/test_kasan_module.c @@ -19,7 +19,7 @@ static noinline void __init copy_user_test(void) { char *kmem; char __user *usermem; - size_t size = 128 - KASAN_GRANULE_SIZE; + volatile size_t size = 128 - KASAN_GRANULE_SIZE; int __maybe_unused unused; kmem = kmalloc(size, GFP_KERNEL); -- 2.30.2
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