[linux-next] LinuxNextTracking branch, master, updated. next-20160919

batman at open-mesh.org batman at open-mesh.org
Tue Sep 20 00:15:40 CEST 2016


The following commit has been merged in the master branch:
commit 936523441bb64cdc9a5b263e8fd2782e70313a57
Author: Sven Eckelmann <sven at narfation.org>
Date:   Sat Aug 6 15:50:52 2016 +0200

    batman-adv: Add missing refcnt for last_candidate
    
    batadv_find_router dereferences last_bonding_candidate from
    orig_node without making sure that it has a valid reference. This reference
    has to be retrieved by increasing the reference counter while holding
    neigh_list_lock. The lock is required to avoid that
    batadv_last_bonding_replace removes the current last_bonding_candidate,
    reduces the reference counter and maybe destroys the object in this
    process.
    
    Fixes: f3b3d9018975 ("batman-adv: add bonding again")
    Signed-off-by: Sven Eckelmann <sven at narfation.org>
    Signed-off-by: Marek Lindner <mareklindner at neomailbox.ch>
    Signed-off-by: Simon Wunderlich <sw at simonwunderlich.de>

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 7602c00..3d19947 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -470,6 +470,29 @@ static int batadv_check_unicast_packet(struct batadv_priv *bat_priv,
 }
 
 /**
+ * batadv_last_bonding_get - Get last_bonding_candidate of orig_node
+ * @orig_node: originator node whose last bonding candidate should be retrieved
+ *
+ * Return: last bonding candidate of router or NULL if not found
+ *
+ * The object is returned with refcounter increased by 1.
+ */
+static struct batadv_orig_ifinfo *
+batadv_last_bonding_get(struct batadv_orig_node *orig_node)
+{
+	struct batadv_orig_ifinfo *last_bonding_candidate;
+
+	spin_lock_bh(&orig_node->neigh_list_lock);
+	last_bonding_candidate = orig_node->last_bonding_candidate;
+
+	if (last_bonding_candidate)
+		kref_get(&last_bonding_candidate->refcount);
+	spin_unlock_bh(&orig_node->neigh_list_lock);
+
+	return last_bonding_candidate;
+}
+
+/**
  * 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
@@ -539,7 +562,7 @@ batadv_find_router(struct batadv_priv *bat_priv,
 	 * router - obviously there are no other candidates.
 	 */
 	rcu_read_lock();
-	last_candidate = orig_node->last_bonding_candidate;
+	last_candidate = batadv_last_bonding_get(orig_node);
 	if (last_candidate)
 		last_cand_router = rcu_dereference(last_candidate->router);
 
@@ -631,6 +654,9 @@ next:
 		batadv_orig_ifinfo_put(next_candidate);
 	}
 
+	if (last_candidate)
+		batadv_orig_ifinfo_put(last_candidate);
+
 	return router;
 }
 

-- 
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