The patch titled
Subject: kasan: add ability to detect double-kmem_cache_destroy()
has been added to the -mm tree. Its filename is
kasan-add-ability-to-detect-double-kmem_cache_destroy.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kasan-add-ability-to-detect-double-kmem_cache_destroy.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kasan-add-ability-to-detect-double-kmem_cache_destroy.patch
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------------------------------------------------------
From: Marco Elver <elver@xxxxxxxxxx>
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@xxxxxxxxxx, which
was not detectable by software KASAN modes.
Link: https://lkml.kernel.org/r/20211119142219.1519617-1-elver@xxxxxxxxxx
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slab_common.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/slab_common.c~kasan-add-ability-to-detect-double-kmem_cache_destroy
+++ a/mm/slab_common.c
@@ -489,7 +489,7 @@ void slab_kmem_cache_release(struct kmem
void kmem_cache_destroy(struct kmem_cache *s)
{
- if (unlikely(!s))
+ if (unlikely(!s) || !kasan_check_byte(s))
return;
cpus_read_lock();
_
Patches currently in -mm which might be from elver@xxxxxxxxxx are
mm-slab_common-use-warn-if-cache-still-has-objects-on-destroy.patch
kasan-test-add-globals-left-out-of-bounds-test.patch
kasan-add-ability-to-detect-double-kmem_cache_destroy.patch
kasan-test-add-test-case-for-double-kmem_cache_destroy.patch
panic-use-error_report_end-tracepoint-on-warnings.patch
