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authorMarco Elver <elver@google.com>2022-01-14 14:04:54 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2022-01-15 16:30:26 +0200
commitbed0a9b591492bb285ea88cd221e0412031396ca (patch)
tree63bba3f5748459fcfad15372d3361871a32a3fb1 /mm
parente5f4728767d2ec9e3eb122c74e224242d21ee650 (diff)
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 <elver@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/slab_common.c2
1 files changed, 1 insertions, 1 deletions
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();