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Commit d5cd9244 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by David S. Miller
Browse files

macvlan: Fix use after free of struct macvlan_port. 



When the macvlan driver was extended to call unregisgter_netdevice_queue
in 23289a37, a use after free of struct
macvlan_port was introduced.  The code in dellink relied on unregister_netdevice
actually unregistering the net device so it would be safe to free macvlan_port.

Since unregister_netdevice_queue can just queue up the unregister instead of
performing the unregiser immediately we free the macvlan_port too soon and
then the code in macvlan_stop removes the macaddress for the set of macaddress
to listen for and uses memory that has already been freed.

To fix this add a reference count to track when it is safe to free the macvlan_port
and move the call of macvlan_port_destroy into macvlan_uninit which is guaranteed
to be called after the final macvlan_port_close.

Signed-off-by: default avatarEric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ac0a121d

drivers/net/macvlan.c

+12 −6
Original line number Diff line number Diff line
@@ -39,8 +39,11 @@ struct macvlan_port { 
	struct list_head	vlans;

	struct rcu_head		rcu;

	bool 			passthru;

	int			count;

};



static void macvlan_port_destroy(struct net_device *dev);



#define macvlan_port_get_rcu(dev) \

	((struct macvlan_port *) rcu_dereference(dev->rx_handler_data))

#define macvlan_port_get(dev) ((struct macvlan_port *) dev->rx_handler_data)
@@ -457,8 +460,13 @@ static int macvlan_init(struct net_device *dev) 
static void macvlan_uninit(struct net_device *dev)

{

	struct macvlan_dev *vlan = netdev_priv(dev);

	struct macvlan_port *port = vlan->port;



	free_percpu(vlan->pcpu_stats);



	port->count -= 1;

	if (!port->count)

		macvlan_port_destroy(port->dev);

}



static struct rtnl_link_stats64 *macvlan_dev_get_stats64(struct net_device *dev,
@@ -691,12 +699,13 @@ int macvlan_common_newlink(struct net *src_net, struct net_device *dev, 
		vlan->mode = nla_get_u32(data[IFLA_MACVLAN_MODE]);



	if (vlan->mode == MACVLAN_MODE_PASSTHRU) {

		if (!list_empty(&port->vlans))

		if (port->count)

			return -EINVAL;

		port->passthru = true;

		memcpy(dev->dev_addr, lowerdev->dev_addr, ETH_ALEN);

	}



	port->count += 1;

	err = register_netdevice(dev);

	if (err < 0)

		goto destroy_port;
@@ -707,7 +716,8 @@ int macvlan_common_newlink(struct net *src_net, struct net_device *dev, 
	return 0;



destroy_port:

	if (list_empty(&port->vlans))

	port->count -= 1;

	if (!port->count)

		macvlan_port_destroy(lowerdev);



	return err;
@@ -725,13 +735,9 @@ static int macvlan_newlink(struct net *src_net, struct net_device *dev, 
void macvlan_dellink(struct net_device *dev, struct list_head *head)

{

	struct macvlan_dev *vlan = netdev_priv(dev);

	struct macvlan_port *port = vlan->port;



	list_del(&vlan->list);

	unregister_netdevice_queue(dev, head);



	if (list_empty(&port->vlans))

		macvlan_port_destroy(port->dev);

}

EXPORT_SYMBOL_GPL(macvlan_dellink);