From: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Subject: kasan: detect invalid frees Detect frees of pointers into middle of heap objects. Link: http://lkml.kernel.org/r/cb569193190356beb018a03bb8d6fbae67e7adbc.1514378558.git.dvyukov@xxxxxxxxxx Signed-off-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>a Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/test_kasan.c | 50 +++++++++++++++++++++++++++++++++++++++++++++ mm/kasan/kasan.c | 6 +++++ 2 files changed, 56 insertions(+) diff -puN lib/test_kasan.c~kasan-detect-invalid-frees lib/test_kasan.c --- a/lib/test_kasan.c~kasan-detect-invalid-frees +++ a/lib/test_kasan.c @@ -523,6 +523,54 @@ static noinline void __init kasan_alloca *(volatile char *)p; } +static noinline void __init kmem_cache_double_free(void) +{ + char *p; + size_t size = 200; + struct kmem_cache *cache; + + cache = kmem_cache_create("test_cache", size, 0, 0, NULL); + if (!cache) { + pr_err("Cache allocation failed\n"); + return; + } + pr_info("double-free on heap object\n"); + p = kmem_cache_alloc(cache, GFP_KERNEL); + if (!p) { + pr_err("Allocation failed\n"); + kmem_cache_destroy(cache); + return; + } + + kmem_cache_free(cache, p); + kmem_cache_free(cache, p); + kmem_cache_destroy(cache); +} + +static noinline void __init kmem_cache_invalid_free(void) +{ + char *p; + size_t size = 200; + struct kmem_cache *cache; + + cache = kmem_cache_create("test_cache", size, 0, SLAB_TYPESAFE_BY_RCU, + NULL); + if (!cache) { + pr_err("Cache allocation failed\n"); + return; + } + pr_info("invalid-free of heap object\n"); + p = kmem_cache_alloc(cache, GFP_KERNEL); + if (!p) { + pr_err("Allocation failed\n"); + kmem_cache_destroy(cache); + return; + } + + kmem_cache_free(cache, p + 1); + kmem_cache_destroy(cache); +} + static int __init kmalloc_tests_init(void) { /* @@ -560,6 +608,8 @@ static int __init kmalloc_tests_init(voi ksize_unpoisons_memory(); copy_user_test(); use_after_scope_test(); + kmem_cache_double_free(); + kmem_cache_invalid_free(); kasan_restore_multi_shot(multishot); diff -puN mm/kasan/kasan.c~kasan-detect-invalid-frees mm/kasan/kasan.c --- a/mm/kasan/kasan.c~kasan-detect-invalid-frees +++ a/mm/kasan/kasan.c @@ -495,6 +495,12 @@ static bool __kasan_slab_free(struct kme s8 shadow_byte; unsigned long rounded_up_size; + if (unlikely(nearest_obj(cache, virt_to_head_page(object), object) != + object)) { + kasan_report_invalid_free(object, ip); + return true; + } + /* RCU slabs could be legally used after free within the RCU period */ if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU)) return false; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
