From: Andrey Konovalov <andreyknvl@xxxxxxxxx> Subject: kasan: test: avoid corrupting memory in copy_user_test copy_user_test() does writes past the allocated object. As the result, it corrupts kernel memory, which might lead to crashes with the HW_TAGS mode, as it neither uses quarantine nor redzones. (Technically, this test can't yet be enabled with the HW_TAGS mode, but this will be implemented in the future.) Adjust the test to only write memory within the aligned kmalloc object. Link: https://lkml.kernel.org/r/19bf3a5112ee65b7db88dc731643b657b816c5e8.1628779805.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_module.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) --- a/lib/test_kasan_module.c~kasan-test-avoid-corrupting-memory-in-copy_user_test +++ a/lib/test_kasan_module.c @@ -15,13 +15,11 @@ #include "../mm/kasan/kasan.h" -#define OOB_TAG_OFF (IS_ENABLED(CONFIG_KASAN_GENERIC) ? 0 : KASAN_GRANULE_SIZE) - static noinline void __init copy_user_test(void) { char *kmem; char __user *usermem; - size_t size = 10; + size_t size = 128 - KASAN_GRANULE_SIZE; int __maybe_unused unused; kmem = kmalloc(size, GFP_KERNEL); @@ -38,25 +36,25 @@ static noinline void __init copy_user_te } pr_info("out-of-bounds in copy_from_user()\n"); - unused = copy_from_user(kmem, usermem, size + 1 + OOB_TAG_OFF); + unused = copy_from_user(kmem, usermem, size + 1); pr_info("out-of-bounds in copy_to_user()\n"); - unused = copy_to_user(usermem, kmem, size + 1 + OOB_TAG_OFF); + unused = copy_to_user(usermem, kmem, size + 1); pr_info("out-of-bounds in __copy_from_user()\n"); - unused = __copy_from_user(kmem, usermem, size + 1 + OOB_TAG_OFF); + unused = __copy_from_user(kmem, usermem, size + 1); pr_info("out-of-bounds in __copy_to_user()\n"); - unused = __copy_to_user(usermem, kmem, size + 1 + OOB_TAG_OFF); + unused = __copy_to_user(usermem, kmem, size + 1); pr_info("out-of-bounds in __copy_from_user_inatomic()\n"); - unused = __copy_from_user_inatomic(kmem, usermem, size + 1 + OOB_TAG_OFF); + unused = __copy_from_user_inatomic(kmem, usermem, size + 1); pr_info("out-of-bounds in __copy_to_user_inatomic()\n"); - unused = __copy_to_user_inatomic(usermem, kmem, size + 1 + OOB_TAG_OFF); + unused = __copy_to_user_inatomic(usermem, kmem, size + 1); pr_info("out-of-bounds in strncpy_from_user()\n"); - unused = strncpy_from_user(kmem, usermem, size + 1 + OOB_TAG_OFF); + unused = strncpy_from_user(kmem, usermem, size + 1); vm_munmap((unsigned long)usermem, PAGE_SIZE); kfree(kmem); _
