ip6_tunnel: copy parms.name after register_netdevice

Commit 1c5cae81 removed an explicit call to dev_alloc_name in ip6_tnl_create
because register_netdevice will now create a valid name.  This works for the
net_device itself.

However the tunnel keeps a copy of the name in the parms structure for the
ip6_tnl associated with the tunnel.  parms.name is set by copying the net_device
name in ip6_tnl_dev_init_gen.  That function is called from ip6_tnl_dev_init in
ip6_tnl_create, but it is done before register_netdevice is called so the name
is set to a bogus value in the parms.name structure.

This shows up if you do a simple tunnel add, followed by a tunnel show:

[root@localhost ~]# ip -6 tunnel add remote fec0::100 local fec0::200
[root@localhost ~]# ip -6 tunnel show
ip6tnl0: ipv6/ipv6 remote :: local :: encaplimit 0 hoplimit 0 tclass 0x00 flowlabel 0x00000 (flowinfo 0x00000000)
ip6tnl%d: ipv6/ipv6 remote fec0::100 local fec0::200 encaplimit 4 hoplimit 64 tclass 0x00 flowlabel 0x00000 (flowinfo 0x00000000)
[root@localhost ~]#

Fix this by moving the strcpy out of ip6_tnl_dev_init_gen, and calling it after
register_netdevice has successfully returned.

Cc: stable@vger.kernel.org
Signed-off-by: Josh Boyer <jwboyer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ip6_tunnel.c

@@ -289,6 +289,8 @@ static struct ip6_tnl *ip6_tnl_create(struct net *net, struct ip6_tnl_parm *p)
 	if ((err = register_netdevice(dev)) < 0)
 		goto failed_free;
 
+	strcpy(t->parms.name, dev->name);
+
 	dev_hold(dev);
 	ip6_tnl_link(ip6n, t);
 	return t;
@@ -1407,7 +1409,6 @@ ip6_tnl_dev_init_gen(struct net_device *dev)
 	struct ip6_tnl *t = netdev_priv(dev);
 
 	t->dev = dev;
-	strcpy(t->parms.name, dev->name);
 	dev->tstats = alloc_percpu(struct pcpu_tstats);
 	if (!dev->tstats)
 		return -ENOMEM;
@@ -1487,6 +1488,7 @@ static void __net_exit ip6_tnl_destroy_tunnels(struct ip6_tnl_net *ip6n)
 static int __net_init ip6_tnl_init_net(struct net *net)
 {
 	struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
+	struct ip6_tnl *t = NULL;
 	int err;
 
 	ip6n->tnls[0] = ip6n->tnls_wc;
@@ -1507,6 +1509,10 @@ static int __net_init ip6_tnl_init_net(struct net *net)
 	err = register_netdev(ip6n->fb_tnl_dev);
 	if (err < 0)
 		goto err_register;
+
+	t = netdev_priv(ip6n->fb_tnl_dev);
+
+	strcpy(t->parms.name, ip6n->fb_tnl_dev->name);
 	return 0;
 
 err_register: