diff options
| author | Marco Elver | 2020-08-06 23:19:12 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2020-08-07 11:33:23 -0700 |
| commit | cfbe1636c3585c1e032bfac512fb8be903fbc913 (patch) | |
| tree | 36503944fe18f9ae48bbe728ea1e4e3a2a729596 /mm | |
| parent | b3cb9fc3aeaf9d52967c87d54a98f035e96279dc (diff) | |
mm, kcsan: instrument SLAB/SLUB free with "ASSERT_EXCLUSIVE_ACCESS"
Provide the necessary KCSAN checks to assist with debugging racy
use-after-frees. While KASAN is more reliable at generally catching such
use-after-frees (due to its use of a quarantine), it can be difficult to
debug racy use-after-frees. If a reliable reproducer exists, KCSAN can
assist in debugging such issues.
Note: ASSERT_EXCLUSIVE_ACCESS is a convenience wrapper if the size is
simply sizeof(var). Instead, here we just use __kcsan_check_access()
explicitly to pass the correct size.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Link: http://lkml.kernel.org/r/20200623072653.114563-1-elver@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/slab.c | 5 | ||||
| -rw-r--r-- | mm/slub.c | 5 |
2 files changed, 10 insertions, 0 deletions
diff --git a/mm/slab.c b/mm/slab.c index 390e249aaa8d..fa31cbb76124 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -3432,6 +3432,11 @@ static __always_inline void __cache_free(struct kmem_cache *cachep, void *objp, if (kasan_slab_free(cachep, objp, _RET_IP_)) return; + /* Use KCSAN to help debug racy use-after-free. */ + if (!(cachep->flags & SLAB_TYPESAFE_BY_RCU)) + __kcsan_check_access(objp, cachep->object_size, + KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ASSERT); + ___cache_free(cachep, objp, caller); } diff --git a/mm/slub.c b/mm/slub.c index e5fc31c37b37..ae39eb392396 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1549,6 +1549,11 @@ static __always_inline bool slab_free_hook(struct kmem_cache *s, void *x) if (!(s->flags & SLAB_DEBUG_OBJECTS)) debug_check_no_obj_freed(x, s->object_size); + /* Use KCSAN to help debug racy use-after-free. */ + if (!(s->flags & SLAB_TYPESAFE_BY_RCU)) + __kcsan_check_access(x, s->object_size, + KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ASSERT); + /* KASAN might put x into memory quarantine, delaying its reuse */ return kasan_slab_free(s, x, _RET_IP_); } |