[PATCH AUTOSEL 4.9 07/27] batman-adv: Fix refcnt leak in batadv_v_ogm_process

[Sasha Levin]

From: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>

[ Upstream commit 6f91a3f7af4186099dd10fa530dd7e0d9c29747d ]

batadv_v_ogm_process() invokes batadv_hardif_neigh_get(), which returns
a reference of the neighbor object to "hardif_neigh" with increased
refcount.

When batadv_v_ogm_process() returns, "hardif_neigh" becomes invalid, so
the refcount should be decreased to keep refcount balanced.

The reference counting issue happens in one exception handling paths of
batadv_v_ogm_process(). When batadv_v_ogm_orig_get() fails to get the
orig node and returns NULL, the refcnt increased by
batadv_hardif_neigh_get() is not decreased, causing a refcnt leak.

Fix this issue by jumping to "out" label when batadv_v_ogm_orig_get()
fails to get the orig node.

Fixes: 9323158ef9f4 ("batman-adv: OGMv2 - implement originators logic")
Signed-off-by: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>
Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx>
Signed-off-by: Sven Eckelmann <sven@xxxxxxxxxxxxx>
Signed-off-by: Simon Wunderlich <sw@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/batman-adv/bat_v_ogm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/batman-adv/bat_v_ogm.c b/net/batman-adv/bat_v_ogm.c
index b0cae59bd327c..d2e6885479cb1 100644
--- a/net/batman-adv/bat_v_ogm.c
+++ b/net/batman-adv/bat_v_ogm.c
@@ -709,7 +709,7 @@ static void batadv_v_ogm_process(const struct sk_buff *skb, int ogm_offset,
 
 	orig_node = batadv_v_ogm_orig_get(bat_priv, ogm_packet->orig);
 	if (!orig_node)
-		return;
+		goto out;
 
 	neigh_node = batadv_neigh_node_get_or_create(orig_node, if_incoming,
 						     ethhdr->h_source);
-- 
2.20.1