batman-adv: Avoid double freeing of bat_counters

On errors in batadv_mesh_init(), bat_counters will be freed in both
batadv_mesh_free() and batadv_softif_init_late(). This patch fixes this
by returning earlier from batadv_softif_init_late() in case of errors in
batadv_mesh_init() and by setting bat_counters to NULL after freeing.
Signed-off-by: Martin Hundebøll <martin@hundeboll.net>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>

net/batman-adv/main.c

@@ -181,6 +181,7 @@ void batadv_mesh_free(struct net_device *soft_iface)
 	batadv_originator_free(bat_priv);
 
 	free_percpu(bat_priv->bat_counters);
+	bat_priv->bat_counters = NULL;
 
 	atomic_set(&bat_priv->mesh_state, BATADV_MESH_INACTIVE);
 }

net/batman-adv/soft-interface.c

@@ -505,6 +505,7 @@ static int batadv_softif_init_late(struct net_device *dev)
 	batadv_debugfs_del_meshif(dev);
 free_bat_counters:
 	free_percpu(bat_priv->bat_counters);
+	bat_priv->bat_counters = NULL;
 
 	return ret;
 }