[PATCH 4.17 096/324] batman-adv: Fix bat_v best gw refcnt after netlink dump

[Greg Kroah-Hartman]

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

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

From: Sven Eckelmann <sven@xxxxxxxxxxxxx>

[ Upstream commit 9713cb0cf19f1cec6c007e3b37be0697042b6720 ]

A reference for the best gateway is taken when the list of gateways in the
mesh is sent via netlink. This is necessary to check whether the currently
dumped entry is the currently selected gateway or not. This information is
then transferred as flag BATADV_ATTR_FLAG_BEST.

After the comparison of the current entry is done,
batadv_v_gw_dump_entry() has to decrease the reference counter again.
Otherwise the reference will be held and thus prevents a proper shutdown of
the batman-adv interfaces (and some of the interfaces enslaved in it).

Fixes: b71bb6f924fe ("batman-adv: add B.A.T.M.A.N. V bat_gw_dump implementations")
Signed-off-by: Sven Eckelmann <sven@xxxxxxxxxxxxx>
Acked-by: Marek Lindner <mareklindner@xxxxxxxxxxxxx>
Signed-off-by: Simon Wunderlich <sw@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/batman-adv/bat_v.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/batman-adv/bat_v.c
+++ b/net/batman-adv/bat_v.c
@@ -927,7 +927,7 @@ static int batadv_v_gw_dump_entry(struct
 {
 	struct batadv_neigh_ifinfo *router_ifinfo = NULL;
 	struct batadv_neigh_node *router;
-	struct batadv_gw_node *curr_gw;
+	struct batadv_gw_node *curr_gw = NULL;
 	int ret = 0;
 	void *hdr;
 
@@ -995,6 +995,8 @@ static int batadv_v_gw_dump_entry(struct
 	ret = 0;
 
 out:
+	if (curr_gw)
+		batadv_gw_node_put(curr_gw);
 	if (router_ifinfo)
 		batadv_neigh_ifinfo_put(router_ifinfo);
 	if (router)