bcache: fix cache_set_flush() NULL pointer dereference on OOM

[ Upstream commit f8b11260a445169989d01df75d35af0f56178f95 ]

When bch_cache_set_alloc() fails to kzalloc the cache_set, the
asyncronous closure handling tries to dereference a cache_set that
hadn't yet been allocated inside of cache_set_flush() which is called
by __cache_set_unregister() during cleanup.  This appears to happen only
during an OOM condition on bcache_register.

Signed-off-by: Eric Wheeler <bcache@linux.ewheeler.net>
Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 2d0650defd3748c36fce4803d68f75acd49451b7..2a102834c2ee03e789b29c50dc8d768119578966 100644 (file)
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1404,6 +1404,9 @@ static void cache_set_flush(struct closure *cl)
        struct btree *b;
        unsigned i;
 
+       if (!c)
+               closure_return(cl);
+
        bch_cache_accounting_destroy(&c->accounting);
 
        kobject_put(&c->internal);