batman-adv: fix potential orig_node reference leak

Since batadv_orig_node_new() sets the refcount to two, assuming that
the calling function will use a reference for putting the orig_node into
a hash or similar, both references must be freed if initialization of
the orig_node fails. Otherwise that object may be leaked in that error
case.
Reported-by: Antonio Quartulli <antonio@meshcoding.com>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>

net/batman-adv/bat_iv_ogm.c

@@ -254,6 +254,8 @@ batadv_iv_ogm_orig_get(struct batadv_priv *bat_priv, const uint8_t *addr)
 free_bcast_own:
 	kfree(orig_node->bat_iv.bcast_own);
 free_orig_node:
+	/* free twice, as batadv_orig_node_new sets refcount to 2 */
+	batadv_orig_node_free_ref(orig_node);
 	batadv_orig_node_free_ref(orig_node);
 
 	return NULL;