Merge tag 'batadv-net-for-davem-20160708' of git://git.open-mesh.org/linux-merge

Simon Wunderlich says:

====================
Here are a couple batman-adv bugfix patches, all by Sven Eckelmann:

 - Fix possible NULL pointer dereference for vlan_insert_tag (two patches)

 - Fix reference handling in some features, which may lead to reference
   leaks or invalid memory access (four patches)

 - Fix speedy join: DHCP packets handled by the gateway feature should
   be sent with 4-address unicast instead of 3-address unicast to make
   speedy join work. This fixes/speeds up DHCP assignment for clients
   which join a mesh for the first time. (one patch)
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 39 insertions, 13 deletions

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 6c2901a86230..bfac086b4d01 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -456,6 +456,29 @@ static int batadv_check_unicast_packet(struct batadv_priv *bat_priv,
 }
 
 /**
+ * batadv_last_bonding_replace - Replace last_bonding_candidate of orig_node
+ * @orig_node: originator node whose bonding candidates should be replaced
+ * @new_candidate: new bonding candidate or NULL
+ */
+static void
+batadv_last_bonding_replace(struct batadv_orig_node *orig_node,
+			    struct batadv_orig_ifinfo *new_candidate)
+{
+	struct batadv_orig_ifinfo *old_candidate;
+
+	spin_lock_bh(&orig_node->neigh_list_lock);
+	old_candidate = orig_node->last_bonding_candidate;
+
+	if (new_candidate)
+		kref_get(&new_candidate->refcount);
+	orig_node->last_bonding_candidate = new_candidate;
+	spin_unlock_bh(&orig_node->neigh_list_lock);
+
+	if (old_candidate)
+		batadv_orig_ifinfo_put(old_candidate);
+}
+
+/**
  * batadv_find_router - find a suitable router for this originator
  * @bat_priv: the bat priv with all the soft interface information
  * @orig_node: the destination node
@@ -562,10 +585,6 @@ next:
 	}
 	rcu_read_unlock();
 
-	/* last_bonding_candidate is reset below, remove the old reference. */
-	if (orig_node->last_bonding_candidate)
-		batadv_orig_ifinfo_put(orig_node->last_bonding_candidate);
-
 	/* After finding candidates, handle the three cases:
 	 * 1) there is a next candidate, use that
 	 * 2) there is no next candidate, use the first of the list
@@ -574,21 +593,28 @@ next:
 	if (next_candidate) {
 		batadv_neigh_node_put(router);
 
-		/* remove references to first candidate, we don't need it. */
-		if (first_candidate) {
-			batadv_neigh_node_put(first_candidate_router);
-			batadv_orig_ifinfo_put(first_candidate);
-		}
+		kref_get(&next_candidate_router->refcount);
 		router = next_candidate_router;
-		orig_node->last_bonding_candidate = next_candidate;
+		batadv_last_bonding_replace(orig_node, next_candidate);
 	} else if (first_candidate) {
 		batadv_neigh_node_put(router);
 
-		/* refcounting has already been done in the loop above. */
+		kref_get(&first_candidate_router->refcount);
 		router = first_candidate_router;
-		orig_node->last_bonding_candidate = first_candidate;
+		batadv_last_bonding_replace(orig_node, first_candidate);
 	} else {
-		orig_node->last_bonding_candidate = NULL;
+		batadv_last_bonding_replace(orig_node, NULL);
+	}
+
+	/* cleanup of candidates */
+	if (first_candidate) {
+		batadv_neigh_node_put(first_candidate_router);
+		batadv_orig_ifinfo_put(first_candidate);
+	}
+
+	if (next_candidate) {
+		batadv_neigh_node_put(next_candidate_router);
+		batadv_orig_ifinfo_put(next_candidate);
 	}
 
 	return router;