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From:   Sasha Levin <sashal@kernel.org>
To:     stable@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Marek Lindner <mareklindner@neomailbox.ch>,
        Sven Eckelmann <sven@narfation.org>,
        Simon Wunderlich <sw@simonwunderlich.de>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH AUTOSEL 4.18 14/58] batman-adv: fix backbone_gw refcount on queue_work() failure
Date:   Mon,  8 Oct 2018 11:24:39 -0400
Message-Id: <20181008152523.70705-14-sashal@kernel.org>
In-Reply-To: <20181008152523.70705-1-sashal@kernel.org>
References: <20181008152523.70705-1-sashal@kernel.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Marek Lindner <mareklindner@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 <mareklindner@neomailbox.ch>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 net/batman-adv/bridge_loop_avoidance.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index a2de5a44bd41..58c093caf49e 100644
--- 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 batadv_priv *bat_priv, struct sk_buff *skb,
 {
 	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 batadv_priv *bat_priv, struct sk_buff *skb,
 	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;
 }
-- 
2.17.1