[linux-next] LinuxNextTracking branch, master, updated. next-20160504

batman at open-mesh.org batman at open-mesh.org
Thu May 5 00:15:45 CEST 2016

The following commit has been merged in the master branch:
commit abe59c65225ccd63a5964e2f2a73dd2995b948e7
Author: Sven Eckelmann <sven at narfation.org>
Date:   Fri Mar 11 16:44:06 2016 +0100

    batman-adv: Fix reference counting of hardif_neigh_node object for neigh_node
    The batadv_neigh_node was specific to a batadv_hardif_neigh_node and held
    an implicit reference to it. But this reference was never stored in form of
    a pointer in the batadv_neigh_node itself. Instead
    batadv_neigh_node_release depends on a consistent state of
    hard_iface->neigh_list and that batadv_hardif_neigh_get always returns the
    batadv_hardif_neigh_node object which it has a reference for. But
    batadv_hardif_neigh_get cannot guarantee that because it is working only
    with rcu_read_lock on this list. It can therefore happen that a neigh_addr
    is in this list twice or that batadv_hardif_neigh_get cannot find the
    batadv_hardif_neigh_node for an neigh_addr due to some other list
    operations taking place at the same time.
    Instead add a batadv_hardif_neigh_node pointer directly in
    batadv_neigh_node which will be used for the reference counter decremented
    on release of batadv_neigh_node.
    Fixes: cef63419f7db ("batman-adv: add list of unique single hop neighbors per hard-interface")
    Signed-off-by: Sven Eckelmann <sven at narfation.org>
    Signed-off-by: Marek Lindner <mareklindner at neomailbox.ch>
    Signed-off-by: Antonio Quartulli <a at unstable.cc>

diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index d52f67a..c355a82 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -250,7 +250,6 @@ static void batadv_neigh_node_release(struct kref *ref)
 	struct hlist_node *node_tmp;
 	struct batadv_neigh_node *neigh_node;
-	struct batadv_hardif_neigh_node *hardif_neigh;
 	struct batadv_neigh_ifinfo *neigh_ifinfo;
 	struct batadv_algo_ops *bao;
@@ -262,13 +261,7 @@ static void batadv_neigh_node_release(struct kref *ref)
-	hardif_neigh = batadv_hardif_neigh_get(neigh_node->if_incoming,
-					       neigh_node->addr);
-	if (hardif_neigh) {
-		/* batadv_hardif_neigh_get() increases refcount too */
-		batadv_hardif_neigh_put(hardif_neigh);
-		batadv_hardif_neigh_put(hardif_neigh);
-	}
+	batadv_hardif_neigh_put(neigh_node->hardif_neigh);
 	if (bao->bat_neigh_free)
@@ -665,6 +658,10 @@ batadv_neigh_node_new(struct batadv_orig_node *orig_node,
 	neigh_node->orig_node = orig_node;
 	neigh_node->last_seen = jiffies;
+	/* increment unique neighbor refcount */
+	kref_get(&hardif_neigh->refcount);
+	neigh_node->hardif_neigh = hardif_neigh;
 	/* extra reference for return */
@@ -673,9 +670,6 @@ batadv_neigh_node_new(struct batadv_orig_node *orig_node,
 	hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list);
-	/* increment unique neighbor refcount */
-	kref_get(&hardif_neigh->refcount);
 	batadv_dbg(BATADV_DBG_BATMAN, orig_node->bat_priv,
 		   "Creating new neighbor %pM for orig_node %pM on interface %s\n",
 		   neigh_addr, orig_node->orig, hard_iface->net_dev->name);
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 65afd09..1e47fbe 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -433,6 +433,7 @@ struct batadv_hardif_neigh_node {
  * @ifinfo_lock: lock protecting private ifinfo members and list
  * @if_incoming: pointer to incoming hard-interface
  * @last_seen: when last packet via this neighbor was received
+ * @hardif_neigh: hardif_neigh of this neighbor
  * @refcount: number of contexts the object is used
  * @rcu: struct used for freeing in an RCU-safe manner
@@ -444,6 +445,7 @@ struct batadv_neigh_node {
 	spinlock_t ifinfo_lock;	/* protects ifinfo_list and its members */
 	struct batadv_hard_iface *if_incoming;
 	unsigned long last_seen;
+	struct batadv_hardif_neigh_node *hardif_neigh;
 	struct kref refcount;
 	struct rcu_head rcu;


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