batman-adv: initialize up/down values when adding a gateway

Without this initialization, gateways which actually announce up/down
bandwidth of 0/0 could be added. If these nodes get purged via
_batadv_purge_orig() later, the gw_node structure does not get removed
since batadv_gw_node_delete() updates the gw_node with up/down
bandwidth of 0/0, and the updating function then discards the change
and does not free gw_node.

This results in leaking the gw_node structures, which references other
structures: gw_node -> orig_node -> orig_node_ifinfo -> hardif. When
removing the interface later, the open reference on the hardif may cause
hangs with the infamous "unregister_netdevice: waiting for mesh1 to
become free. Usage count = 1" message.
Signed-off-by: NSimon Wunderlich <simon@open-mesh.com>
Signed-off-by: NMarek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: NAntonio Quartulli <antonio@meshcoding.com>

net/batman-adv/gateway_client.c

@@ -439,6 +439,8 @@ static void batadv_gw_node_add(struct batadv_priv *bat_priv,
 
 	INIT_HLIST_NODE(&gw_node->list);
 	gw_node->orig_node = orig_node;
+	gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
+	gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
 	atomic_set(&gw_node->refcount, 1);
 
 	spin_lock_bh(&bat_priv->gw.list_lock);