net: ip6_tunnel: Unregister catch-all devices

stable inclusion
from linux-4.19.189
commit e4cb6ee364ddd274c4faf5cb4baa1c397c72584b

--------------------------------

commit 941ea91e upstream.

Similarly to the sit case, we need to remove the tunnels with no
addresses that have been moved to another network namespace.

Fixes: 0bd87628 ("ip6tnl: add x-netns support")
Signed-off-by: NHristo Venev <hristo@venev.name>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

net/ipv6/ip6_tunnel.c

@@ -2222,6 +2222,16 @@ static void __net_exit ip6_tnl_destroy_tunnels(struct net *net, struct list_head
 			t = rtnl_dereference(t->next);
 		}
 	}
+
+	t = rtnl_dereference(ip6n->tnls_wc[0]);
+	while (t) {
+		/* If dev is in the same netns, it has already
+		 * been added to the list by the previous loop.
+		 */
+		if (!net_eq(dev_net(t->dev), net))
+			unregister_netdevice_queue(t->dev, list);
+		t = rtnl_dereference(t->next);
+	}
 }
 
 static int __net_init ip6_tnl_init_net(struct net *net)