[PATCH 4.18 14/53] batman-adv: fix backbone_gw refcount on queue_work() failure

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marek Lindner <mareklind...@neomailbox.ch>

[ Upstream commit 5af96b9c59c72fb2af2d19c5cc2f3cdcee391dff ]

The backbone_gw refcounter is to be decreased by the queued work and
currently is never decreased if the queue_work() call fails.
Fix by checking the queue_work() return value and decrease refcount
if necessary.

Signed-off-by: Marek Lindner <mareklind...@neomailbox.ch>
Signed-off-by: Sven Eckelmann <s...@narfation.org>
Signed-off-by: Simon Wunderlich <s...@simonwunderlich.de>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 net/batman-adv/bridge_loop_avoidance.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -1772,6 +1772,7 @@ batadv_bla_loopdetect_check(struct batad
 {
        struct batadv_bla_backbone_gw *backbone_gw;
        struct ethhdr *ethhdr;
+       bool ret;
 
        ethhdr = eth_hdr(skb);
 
@@ -1795,8 +1796,13 @@ batadv_bla_loopdetect_check(struct batad
        if (unlikely(!backbone_gw))
                return true;
 
-       queue_work(batadv_event_workqueue, &backbone_gw->report_work);
-       /* backbone_gw is unreferenced in the report work function function */
+       ret = queue_work(batadv_event_workqueue, &backbone_gw->report_work);
+
+       /* backbone_gw is unreferenced in the report work function function
+        * if queue_work() call was successful
+        */
+       if (!ret)
+               batadv_backbone_gw_put(backbone_gw);
 
        return true;
 }