mac80211_hwsim: fix error handling in tx_frame_nl

Correct two problems with the error handling when using the netlink
forwarding API: first, the netlink skb is never freed if nla_put()
fails; and second, genlmsg_unicast() can fail if the netlink socket
is full.  In the latter case, the corresponding data skb is not counted
as a drop and userspace programs like wmediumd will see TCP stalls
due to lost packets.
Signed-off-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/mac80211_hwsim.c

@@ -946,7 +946,8 @@ static void mac80211_hwsim_tx_frame_nl(struct ieee80211_hw *hw,
 		goto nla_put_failure;
 
 	genlmsg_end(skb, msg_head);
-	genlmsg_unicast(&init_net, skb, dst_portid);
+	if (genlmsg_unicast(&init_net, skb, dst_portid))
+		goto err_free_txskb;
 
 	/* Enqueue the packet */
 	skb_queue_tail(&data->pending, my_skb);
@@ -955,6 +956,8 @@ static void mac80211_hwsim_tx_frame_nl(struct ieee80211_hw *hw,
 	return;
 
 nla_put_failure:
+	nlmsg_free(skb);
+err_free_txskb:
 	printk(KERN_DEBUG "mac80211_hwsim: error occurred in %s\n", __func__);
 	ieee80211_free_txskb(hw, my_skb);
 	data->tx_failed++;