net: fib_rules ordering fixes.

We need to setup the network namespace state before we register
the notifier.  Otherwise if a network device is already registered
we get a nasty NULL pointer dereference.

Signed-off-by: Eric W. Biederman <ebiederm@maxwell.aristanetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/fib_rules.c

@@ -664,17 +664,18 @@ static int __init fib_rules_init(void)
 	rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL);
 	rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule);
 
-	err = register_netdevice_notifier(&fib_rules_notifier);
+	err = register_pernet_subsys(&fib_rules_net_ops);
 	if (err < 0)
 		goto fail;
 
-	err = register_pernet_subsys(&fib_rules_net_ops);
+	err = register_netdevice_notifier(&fib_rules_notifier);
 	if (err < 0)
 		goto fail_unregister;
+
 	return 0;
 
 fail_unregister:
-	unregister_netdevice_notifier(&fib_rules_notifier);
+	unregister_pernet_subsys(&fib_rules_net_ops);
 fail:
 	rtnl_unregister(PF_UNSPEC, RTM_NEWRULE);
 	rtnl_unregister(PF_UNSPEC, RTM_DELRULE);