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| author | Shakeel Butt <shakeelb@google.com> | 2020-09-26 07:13:41 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-09-26 10:15:01 -0700 |
| commit | 678ff6a7afccc43d352c1b8c94b6d8c0ee1464ad (patch) | |
| tree | 5e8da2d0d8687dc174f0987e8bd29a82e3ba73cd /mm/slab.c | |
| parent | 7c7ec3226f5f33f9c050d85ec20f18419c622ad6 (diff) | |
| download | linux-678ff6a7afccc43d352c1b8c94b6d8c0ee1464ad.tar.bz2 | |
mm: slab: fix potential double free in ___cache_free
With the commit 10befea91b61 ("mm: memcg/slab: use a single set of
kmem_caches for all allocations"), it becomes possible to call kfree()
from the slabs_destroy().
The functions cache_flusharray() and do_drain() calls slabs_destroy() on
array_cache of the local CPU without updating the size of the
array_cache. This enables the kfree() call from the slabs_destroy() to
recursively call cache_flusharray() which can potentially call
free_block() on the same elements of the array_cache of the local CPU
and causing double free and memory corruption.
To fix the issue, simply update the local CPU array_cache cache before
calling slabs_destroy().
Fixes: 10befea91b61 ("mm: memcg/slab: use a single set of kmem_caches for all allocations")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Reported-by: kernel test robot <rong.a.chen@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ted Ts'o <tytso@mit.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slab.c')
| -rw-r--r-- | mm/slab.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/mm/slab.c b/mm/slab.c index 3160dff6fd76..f658e86ec8ce 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -1632,6 +1632,10 @@ static void slab_destroy(struct kmem_cache *cachep, struct page *page) kmem_cache_free(cachep->freelist_cache, freelist); } +/* + * Update the size of the caches before calling slabs_destroy as it may + * recursively call kfree. + */ static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list) { struct page *page, *n; @@ -2153,8 +2157,8 @@ static void do_drain(void *arg) spin_lock(&n->list_lock); free_block(cachep, ac->entry, ac->avail, node, &list); spin_unlock(&n->list_lock); - slabs_destroy(cachep, &list); ac->avail = 0; + slabs_destroy(cachep, &list); } static void drain_cpu_caches(struct kmem_cache *cachep) @@ -3402,9 +3406,9 @@ free_done: } #endif spin_unlock(&n->list_lock); - slabs_destroy(cachep, &list); ac->avail -= batchcount; memmove(ac->entry, &(ac->entry[batchcount]), sizeof(void *)*ac->avail); + slabs_destroy(cachep, &list); } /* |