If del_nbp()->cancel_delayed_work(carrier_check) fails, port_carrier_check()
may run later and access an already freed container (struct net_bridge_port).
With this patch, carrier_check owns a reference to "struct net_bridge_port",
not net_device, so it is always safe to acces the container.
port_carrier_check() uses p->dev->br_port == NULL as indication that net_bridge_port
is under destruction. Otherwise it assumes that p->dev->br_port == p.
Signed-off-by: Oleg Nesterov <[email protected]>
Acked-By: David Howells <[email protected]>
--- WQ/net/bridge/br_if.c~5_bridge_uaf 2007-02-18 23:06:15.000000000 +0300
+++ WQ/net/bridge/br_if.c 2007-02-20 00:59:54.000000000 +0300
@@ -83,14 +83,14 @@ static void port_carrier_check(struct wo
struct net_device *dev;
struct net_bridge *br;
- dev = container_of(work, struct net_bridge_port,
- carrier_check.work)->dev;
+ p = container_of(work, struct net_bridge_port, carrier_check.work);
rtnl_lock();
- p = dev->br_port;
- if (!p)
- goto done;
br = p->br;
+ dev = p->dev;
+
+ if (!dev->br_port)
+ goto done;
if (netif_carrier_ok(dev))
p->path_cost = port_cost(dev);
@@ -107,14 +107,16 @@ static void port_carrier_check(struct wo
spin_unlock_bh(&br->lock);
}
done:
- dev_put(dev);
rtnl_unlock();
+ kobject_put(&p->kobj);
}
static void release_nbp(struct kobject *kobj)
{
struct net_bridge_port *p
= container_of(kobj, struct net_bridge_port, kobj);
+
+ dev_put(p->dev);
kfree(p);
}
@@ -127,12 +129,6 @@ static struct kobj_type brport_ktype = {
static void destroy_nbp(struct net_bridge_port *p)
{
- struct net_device *dev = p->dev;
-
- p->br = NULL;
- p->dev = NULL;
- dev_put(dev);
-
kobject_put(&p->kobj);
}
@@ -162,7 +158,7 @@ static void del_nbp(struct net_bridge_po
dev_set_promiscuity(dev, -1);
if (cancel_delayed_work(&p->carrier_check))
- dev_put(dev);
+ kobject_put(&p->kobj);
spin_lock_bh(&br->lock);
br_stp_disable_port(p);
@@ -446,7 +442,7 @@ int br_add_if(struct net_bridge *br, str
br_stp_recalculate_bridge_id(br);
br_features_recompute(br);
if (schedule_delayed_work(&p->carrier_check, BR_PORT_DEBOUNCE))
- dev_hold(dev);
+ kobject_get(&p->kobj);
spin_unlock_bh(&br->lock);
-
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