From: Andrey Konovalov <andreyknvl@xxxxxxxxx> Subject: kasan: test: avoid corrupting memory via memset kmalloc_oob_memset_*() tests do writes past the allocated objects. As the result, they corrupt memory, which might lead to crashes with the HW_TAGS mode, as it neither uses quarantine nor redzones. Adjust the tests to only write memory within the aligned kmalloc objects. Also add a comment mentioning that memset tests are designed to touch both valid and invalid memory. Link: https://lkml.kernel.org/r/64fd457668a16e7b58d094f14a165f9d5170c5a9.1628779805.git.andreyknvl@xxxxxxxxx Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxx> Reviewed-by: Marco Elver <elver@xxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/test_kasan.c | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-) --- a/lib/test_kasan.c~kasan-test-avoid-corrupting-memory-via-memset +++ a/lib/test_kasan.c @@ -428,64 +428,70 @@ static void kmalloc_uaf_16(struct kunit kfree(ptr1); } +/* + * Note: in the memset tests below, the written range touches both valid and + * invalid memory. This makes sure that the instrumentation does not only check + * the starting address but the whole range. + */ + static void kmalloc_oob_memset_2(struct kunit *test) { char *ptr; - size_t size = 8; + size_t size = 128 - KASAN_GRANULE_SIZE; ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); - KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + 7 + OOB_TAG_OFF, 0, 2)); + KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 1, 0, 2)); kfree(ptr); } static void kmalloc_oob_memset_4(struct kunit *test) { char *ptr; - size_t size = 8; + size_t size = 128 - KASAN_GRANULE_SIZE; ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); - KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + 5 + OOB_TAG_OFF, 0, 4)); + KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 3, 0, 4)); kfree(ptr); } - static void kmalloc_oob_memset_8(struct kunit *test) { char *ptr; - size_t size = 8; + size_t size = 128 - KASAN_GRANULE_SIZE; ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); - KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + 1 + OOB_TAG_OFF, 0, 8)); + KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 7, 0, 8)); kfree(ptr); } static void kmalloc_oob_memset_16(struct kunit *test) { char *ptr; - size_t size = 16; + size_t size = 128 - KASAN_GRANULE_SIZE; ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); - KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + 1 + OOB_TAG_OFF, 0, 16)); + KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 15, 0, 16)); kfree(ptr); } static void kmalloc_oob_in_memset(struct kunit *test) { char *ptr; - size_t size = 666; + size_t size = 128 - KASAN_GRANULE_SIZE; ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); - KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr, 0, size + 5 + OOB_TAG_OFF)); + KUNIT_EXPECT_KASAN_FAIL(test, + memset(ptr, 0, size + KASAN_GRANULE_SIZE)); kfree(ptr); } _
