[PATCH] netpoll: fix null ifa_list pointer dereference

This fixes a bug where netpoll can dereference a null ifa_list pointer when
not supplied an IP address at module load and the interface is up but no IP
is configured.

Bonus: unrelated netif_running cleanup

Signed-off by: Jeff Moyer <jmoyer@redhat.com>
Signed-off by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

net/core/netpoll.c

@@ -565,7 +565,7 @@ int netpoll_setup(struct netpoll *np)
 		goto release;
 	}
 
-	if (!(ndev->flags & IFF_UP)) {
+	if (!netif_running(ndev)) {
 		unsigned short oflags;
 		unsigned long atmost, atleast;
 
@@ -611,7 +611,7 @@ int netpoll_setup(struct netpoll *np)
 		rcu_read_lock();
 		in_dev = __in_dev_get(ndev);
 
-		if (!in_dev) {
+		if (!in_dev || !in_dev->ifa_list) {
 			rcu_read_unlock();
 			printk(KERN_ERR "%s: no IP address for %s, aborting\n",
 			       np->name, np->dev_name);