[linux-next] LinuxNextTracking branch, master, updated. next-20180921

batman at open-mesh.org batman at open-mesh.org
Sat Sep 22 00:20:37 CEST 2018

The following commit has been merged in the master branch:
commit dff9bc42ab0b2d38c5e90ddd79b238fed5b4c7ad
Author: Sven Eckelmann <sven at narfation.org>
Date:   Sun Aug 12 21:04:41 2018 +0200

    batman-adv: Prevent duplicated gateway_node entry
    The function batadv_gw_node_add is responsible for adding new gw_node to
    the gateway_list. It is expecting that the caller already checked that
    there is not already an entry with the same key or not.
    But the lock for the list is only held when the list is really modified.
    This could lead to duplicated entries because another context could create
    an entry with the same key between the check and the list manipulation.
    The check and the manipulation of the list must therefore be in the same
    locked code section.
    Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol")
    Signed-off-by: Sven Eckelmann <sven at narfation.org>
    Acked-by: Marek Lindner <mareklindner at neomailbox.ch>
    Signed-off-by: Simon Wunderlich <sw at simonwunderlich.de>

diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
index 8b198ee798c9..140c61a3f1ec 100644
--- a/net/batman-adv/gateway_client.c
+++ b/net/batman-adv/gateway_client.c
@@ -32,6 +32,7 @@
 #include <linux/kernel.h>
 #include <linux/kref.h>
 #include <linux/list.h>
+#include <linux/lockdep.h>
 #include <linux/netdevice.h>
 #include <linux/netlink.h>
 #include <linux/rculist.h>
@@ -348,6 +349,9 @@ out:
  * @bat_priv: the bat priv with all the soft interface information
  * @orig_node: originator announcing gateway capabilities
  * @gateway: announced bandwidth information
+ *
+ * Has to be called with the appropriate locks being acquired
+ * (gw.list_lock).
 static void batadv_gw_node_add(struct batadv_priv *bat_priv,
 			       struct batadv_orig_node *orig_node,
@@ -355,6 +359,8 @@ static void batadv_gw_node_add(struct batadv_priv *bat_priv,
 	struct batadv_gw_node *gw_node;
+	lockdep_assert_held(&bat_priv->gw.list_lock);
 	if (gateway->bandwidth_down == 0)
@@ -369,10 +375,8 @@ static void batadv_gw_node_add(struct batadv_priv *bat_priv,
 	gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
 	gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
-	spin_lock_bh(&bat_priv->gw.list_lock);
 	hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.gateway_list);
-	spin_unlock_bh(&bat_priv->gw.list_lock);
 	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 		   "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n",
@@ -428,11 +432,14 @@ void batadv_gw_node_update(struct batadv_priv *bat_priv,
 	struct batadv_gw_node *gw_node, *curr_gw = NULL;
+	spin_lock_bh(&bat_priv->gw.list_lock);
 	gw_node = batadv_gw_node_get(bat_priv, orig_node);
 	if (!gw_node) {
 		batadv_gw_node_add(bat_priv, orig_node, gateway);
+		spin_unlock_bh(&bat_priv->gw.list_lock);
 		goto out;
+	spin_unlock_bh(&bat_priv->gw.list_lock);
 	if (gw_node->bandwidth_down == ntohl(gateway->bandwidth_down) &&
 	    gw_node->bandwidth_up == ntohl(gateway->bandwidth_up))


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