From bed0a9b591492bb285ea88cd221e0412031396ca Mon Sep 17 00:00:00 2001 From: Marco Elver Date: Fri, 14 Jan 2022 14:04:54 -0800 Subject: kasan: add ability to detect double-kmem_cache_destroy() Because mm/slab_common.c is not instrumented with software KASAN modes, it is not possible to detect use-after-free of the kmem_cache passed into kmem_cache_destroy(). In particular, because of the s->refcount-- and subsequent early return if non-zero, KASAN would never be able to see the double-free via kmem_cache_free(kmem_cache, s). To be able to detect a double-kmem_cache_destroy(), check accessibility of the kmem_cache, and in case of failure return early. While KASAN_HW_TAGS is able to detect such bugs, by checking accessibility and returning early we fail more gracefully and also avoid corrupting reused objects (where tags mismatch). A recent case of a double-kmem_cache_destroy() was detected by KFENCE: https://lkml.kernel.org/r/0000000000003f654905c168b09d@google.com, which was not detectable by software KASAN modes. Link: https://lkml.kernel.org/r/20211119142219.1519617-1-elver@google.com Signed-off-by: Marco Elver Acked-by: Vlastimil Babka Reviewed-by: Andrey Konovalov Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Christoph Lameter Cc: David Rientjes Cc: Dmitry Vyukov Cc: Joonsoo Kim Cc: Pekka Enberg Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/slab_common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm/slab_common.c') diff --git a/mm/slab_common.c b/mm/slab_common.c index b7c431819cdb..f02c32bd05ab 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -489,7 +489,7 @@ void slab_kmem_cache_release(struct kmem_cache *s) void kmem_cache_destroy(struct kmem_cache *s) { - if (unlikely(!s)) + if (unlikely(!s) || !kasan_check_byte(s)) return; cpus_read_lock(); -- cgit v1.2.3