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: v4.1.12-92~150^2~58
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=a8ff421a3e97c8a5a89208efc1621e88f48fde5f;p=users%2Fjedix%2Flinux-maple.git

bcache: fix cache_set_flush() NULL pointer dereference on OOM

Orabug: 23331099

[ 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>
(cherry picked from commit d09a05998d79dcfaa25de84624dce9f806fe4e7c)

Signed-off-by: Dan Duval <dan.duval@oracle.com>
---

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 2d0650defd37..2a102834c2ee 100644
--- 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);