rtnetlink: call ->dellink on failure when ->newlink exists

[ Upstream commit 7afb8886a05be68e376655539a064ec672de8a8e ]

Ignacy reported that when eth0 is down and add a vlan device
on top of it like:

  ip link add link eth0 name eth0.1 up type vlan id 1

We will get a refcount leak:

  unregister_netdevice: waiting for eth0.1 to become free. Usage count = 2

The problem is when rtnl_configure_link() fails in rtnl_newlink(),
we simply call unregister_device(), but for stacked device like vlan,
we almost do nothing when we unregister the upper device, more work
is done when we unregister the lower device, so call its ->dellink().

Reported-by: Ignacy Gawedzki <ignacy.gawedzki@green-communications.fr>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 2c51dfb..5b412f0 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1860,8 +1860,16 @@ replay:
                        goto out;
 
                err = rtnl_configure_link(dev, ifm);
                        goto out;
 
                err = rtnl_configure_link(dev, ifm);

-               if (err < 0)
-                       unregister_netdevice(dev);
+               if (err < 0) {
+                       if (ops->newlink) {
+                               LIST_HEAD(list_kill);
+
+                               ops->dellink(dev, &list_kill);
+                               unregister_netdevice_many(&list_kill);
+                       } else {
+                               unregister_netdevice(dev);
+                       }
+               }

 out:
                put_net(dest_net);
                return err;
 out:
                put_net(dest_net);
                return err;