batman-adv: Free last_bonding_candidate on release of orig_node

BugLink: https://bugs.launchpad.net/bugs/1868629

commit cbef1e10 upstream.

The orig_ifinfo reference counter for last_bonding_candidate in
batadv_orig_node has to be reduced when an originator node is released.
Otherwise the orig_ifinfo is leaked and the reference counter the netdevice
is not reduced correctly.

Fixes: f3b3d901 ("batman-adv: add bonding again")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

net/batman-adv/originator.c

@@ -565,6 +565,7 @@ static void batadv_orig_node_release(struct batadv_orig_node *orig_node)
 	struct batadv_neigh_node *neigh_node;
 	struct batadv_orig_ifinfo *orig_ifinfo;
 	struct batadv_orig_node_vlan *vlan;
+	struct batadv_orig_ifinfo *last_candidate;
 
 	spin_lock_bh(&orig_node->neigh_list_lock);
 
@@ -580,8 +581,14 @@ static void batadv_orig_node_release(struct batadv_orig_node *orig_node)
 		hlist_del_rcu(&orig_ifinfo->list);
 		batadv_orig_ifinfo_free_ref(orig_ifinfo);
 	}
+
+	last_candidate = orig_node->last_bonding_candidate;
+	orig_node->last_bonding_candidate = NULL;
 	spin_unlock_bh(&orig_node->neigh_list_lock);
 
+	if (last_candidate)
+		batadv_orig_ifinfo_free_ref(last_candidate);
+
 	spin_lock_bh(&orig_node->vlan_list_lock);
 	hlist_for_each_entry_safe(vlan, node_tmp, &orig_node->vlan_list, list) {
 		hlist_del_rcu(&vlan->list);