Commit 09c2e76e authored Jan 08, 2019 by Christoph Lameter Committed by Linus Torvalds Jan 08, 2019

slab: alien caches must not be initialized if the allocation of the alien cache failed

Callers of __alloc_alien() check for NULL.  We must do the same check in
__alloc_alien_cache to avoid NULL pointer dereferences on allocation
failures.

Link: http://lkml.kernel.org/r/010001680f42f192-82b4e12e-1565-4ee0-ae1f-1e98974906aa-000000@email.amazonses.com


Fixes: 49dfc304 ("slab: use the lock on alien_cache, instead of the lock on array_cache")
Fixes: c8522a3a ("Slab: introduce alloc_alien")
Signed-off-by: Christoph Lameter <cl@linux.com>
Reported-by:  <syzbot+d6ed4ec679652b4fd4e4@syzkaller.appspotmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ba4a4574

mm/slab.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -666,8 +666,10 @@ static struct alien_cache *__alloc_alien_cache(int node, int entries,
		struct alien_cache *alc = NULL;

		alc = kmalloc_node(memsize, gfp, node);
		if (alc) {
		init_arraycache(&alc->ac, entries, batch);
		spin_lock_init(&alc->lock);
		}
		return alc;
		}

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