bridge: Partially disable netpoll support

The new netpoll code in bridging contains use-after-free bugs
that are non-trivial to fix.

This patch fixes this by removing the code that uses skbs after
they're freed.

As a consequence, this means that we can no longer call bridge
from the netpoll path, so this patch also removes the controller
function in order to disable netpoll.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Thanks,
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_device.c

@@ -217,14 +217,6 @@ static bool br_devices_support_netpoll(struct net_bridge *br)
 	return count != 0 && ret;
 }
 
-static void br_poll_controller(struct net_device *br_dev)
-{
-	struct netpoll *np = br_dev->npinfo->netpoll;
-
-	if (np->real_dev != br_dev)
-		netpoll_poll_dev(np->real_dev);
-}
-
 void br_netpoll_cleanup(struct net_device *dev)
 {
 	struct net_bridge *br = netdev_priv(dev);
@@ -295,7 +287,6 @@ static const struct net_device_ops br_netdev_ops = {
 	.ndo_do_ioctl		 = br_dev_ioctl,
 #ifdef CONFIG_NET_POLL_CONTROLLER
 	.ndo_netpoll_cleanup	 = br_netpoll_cleanup,
-	.ndo_poll_controller	 = br_poll_controller,
 #endif
 };
 

net/bridge/br_forward.c

@@ -50,13 +50,6 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
 			kfree_skb(skb);
 		else {
 			skb_push(skb, ETH_HLEN);
-
-#ifdef CONFIG_NET_POLL_CONTROLLER
-			if (unlikely(skb->dev->priv_flags & IFF_IN_NETPOLL)) {
-				netpoll_send_skb(skb->dev->npinfo->netpoll, skb);
-				skb->dev->priv_flags &= ~IFF_IN_NETPOLL;
-			} else
-#endif
 			dev_queue_xmit(skb);
 		}
 	}
@@ -73,23 +66,9 @@ int br_forward_finish(struct sk_buff *skb)
 
 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 {
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	struct net_bridge *br = to->br;
-	if (unlikely(br->dev->priv_flags & IFF_IN_NETPOLL)) {
-		struct netpoll *np;
-		to->dev->npinfo = skb->dev->npinfo;
-		np = skb->dev->npinfo->netpoll;
-		np->real_dev = np->dev = to->dev;
-		to->dev->priv_flags |= IFF_IN_NETPOLL;
-	}
-#endif
 	skb->dev = to->dev;
 	NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
 		br_forward_finish);
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	if (skb->dev->npinfo)
-		skb->dev->npinfo->netpoll->dev = br->dev;
-#endif
 }
 
 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)