Commit 7ea7c076 authored by Sven Eckelmann's avatar Sven Eckelmann Committed by Kelsey Skunberg

batman-adv: Prevent duplicated gateway_node entry

BugLink: https://bugs.launchpad.net/bugs/1868629

commit dff9bc42 upstream.

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: c6c8fea2 ("net: Add batman-adv meshing protocol")
Signed-off-by: default avatarSven Eckelmann <sven@narfation.org>
Acked-by: default avatarMarek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: default avatarSimon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarKhalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: default avatarKelsey Skunberg <kelsey.skunberg@canonical.com>
parent c5fe9914
......@@ -29,6 +29,7 @@
#include <linux/ipv6.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/lockdep.h>
#include <linux/netdevice.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
......@@ -413,6 +414,9 @@ void batadv_gw_check_election(struct batadv_priv *bat_priv,
* @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,
......@@ -420,6 +424,8 @@ 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)
return;
......@@ -438,9 +444,7 @@ static void batadv_gw_node_add(struct batadv_priv *bat_priv,
gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
atomic_set(&gw_node->refcount, 1);
spin_lock_bh(&bat_priv->gw.list_lock);
hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.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",
......@@ -493,11 +497,14 @@ 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)))
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment