macvlan: Fix one possible double free

Because the macvlan_uninit would free the macvlan port, so there is one
double free case in macvlan_common_newlink. When the macvlan port is just
created, then register_netdevice or netdev_upper_dev_link failed and they
would invoke macvlan_uninit. Then it would reach the macvlan_port_destroy
which triggers the double free.

Signed-off-by: Gao Feng <gfree.wind@vip.163.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index a178c5efd33e5486d47608dd7e4d7218b8eda4a1..a0f2be81d52e4a4fd24585d8957b181a3cf9a103 100644 (file)
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -1444,9 +1444,14 @@ int macvlan_common_newlink(struct net *src_net, struct net_device *dev,
        return 0;
 
 unregister_netdev:
+       /* macvlan_uninit would free the macvlan port */
        unregister_netdevice(dev);
+       return err;
 destroy_macvlan_port:
-       if (create)
+       /* the macvlan port may be freed by macvlan_uninit when fail to register.
+        * so we destroy the macvlan port only when it's valid.
+        */
+       if (create && macvlan_port_get_rtnl(dev))
                macvlan_port_destroy(port->dev);
        return err;
 }