Linux-libre 4.5.4-gnupck-4.5.4-gnu

1 files changed, 9 insertions, 0 deletions

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index e4f2646d9..43d15d6c4 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -104,6 +104,15 @@ static void _batadv_update_route(struct batadv_priv *bat_priv,
 		neigh_node = NULL;
 
 	spin_lock_bh(&orig_node->neigh_list_lock);
+	/* curr_router used earlier may not be the current orig_ifinfo->router
+	 * anymore because it was dereferenced outside of the neigh_list_lock
+	 * protected region. After the new best neighbor has replace the current
+	 * best neighbor the reference counter needs to decrease. Consequently,
+	 * the code needs to ensure the curr_router variable contains a pointer
+	 * to the replaced best neighbor.
+	 */
+	curr_router = rcu_dereference_protected(orig_ifinfo->router, true);
+
 	rcu_assign_pointer(orig_ifinfo->router, neigh_node);
 	spin_unlock_bh(&orig_node->neigh_list_lock);
 	batadv_orig_ifinfo_free_ref(orig_ifinfo);