From: Eric Wheeler <git@linux.ewheeler.net>
Date: Mon, 7 Mar 2016 23:17:50 +0000 (-0800)
Subject: bcache: fix cache_set_flush() NULL pointer dereference on OOM
X-Git-Tag: v3.16.35~135
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=456aee7e1f2bc28775a13abd3f6395aae49cf9b4;p=thirdparty%2Fkernel%2Fstable.git

bcache: fix cache_set_flush() NULL pointer dereference on OOM

commit f8b11260a445169989d01df75d35af0f56178f95 upstream.

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 034501d5b3399..3b260c67db751 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1385,6 +1385,9 @@ 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);