ieee802154: fix iface dump with lowpan

This patch adds a hacked solution for an interface dump with a running
lowpan interface. This will crash because lowpan and wpan interface use
the same arphdr. To change the arphdr will change the UAPI, this patch
checks on mtu which should on lowpan interface always different than
IEEE802154_MTU.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/ieee802154/nl-mac.c

@@ -166,7 +166,10 @@ static struct net_device *ieee802154_nl_get_dev(struct genl_info *info)
 	if (!dev)
 		return NULL;
 
-	if (dev->type != ARPHRD_IEEE802154) {
+	/* Check on mtu is currently a hacked solution because lowpan
+	 * and wpan have the same ARPHRD type.
+	 */
+	if (dev->type != ARPHRD_IEEE802154 || dev->mtu != IEEE802154_MTU) {
 		dev_put(dev);
 		return NULL;
 	}
@@ -448,7 +451,11 @@ int ieee802154_dump_iface(struct sk_buff *skb, struct netlink_callback *cb)
 
 	idx = 0;
 	for_each_netdev(net, dev) {
-		if (idx < s_idx || (dev->type != ARPHRD_IEEE802154))
+		/* Check on mtu is currently a hacked solution because lowpan
+		 * and wpan have the same ARPHRD type.
+		 */
+		if (idx < s_idx || dev->type != ARPHRD_IEEE802154 ||
+		    dev->mtu != IEEE802154_MTU)
 			goto cont;
 
 		if (ieee802154_nl_fill_iface(skb, NETLINK_CB(cb->skb).portid,
@@ -782,7 +789,11 @@ ieee802154_llsec_dump_table(struct sk_buff *skb, struct netlink_callback *cb,
 	int rc;
 
 	for_each_netdev(net, dev) {
-		if (idx < first_dev || dev->type != ARPHRD_IEEE802154)
+		/* Check on mtu is currently a hacked solution because lowpan
+		 * and wpan have the same ARPHRD type.
+		 */
+		if (idx < first_dev || dev->type != ARPHRD_IEEE802154 ||
+		    dev->mtu != IEEE802154_MTU)
 			goto skip;
 
 		data.ops = ieee802154_mlme_ops(dev);