tipc: fix a memory leak in tipc_nl_node_get_link()

When tipc_node_find_by_name() fails, the nlmsg is not
freed.

While on it, switch to a goto label to properly
free it.

Fixes: be9c086715c ("tipc: narrow down exposure of struct tipc_node")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Jon Maloy <jon.maloy@ericsson.com>
Cc: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/node.c

@@ -1880,36 +1880,38 @@ int tipc_nl_node_get_link(struct sk_buff *skb, struct genl_info *info)
 
 	if (strcmp(name, tipc_bclink_name) == 0) {
 		err = tipc_nl_add_bc_link(net, &msg);
-		if (err) {
+		if (err)
-			nlmsg_free(msg.skb);
+			goto err_free;
-			return err;
-		}
 	} else {
 		int bearer_id;
 		struct tipc_node *node;
 		struct tipc_link *link;
 
 		node = tipc_node_find_by_name(net, name, &bearer_id);
-		if (!node)
+		if (!node) {
-			return -EINVAL;
+			err = -EINVAL;
+			goto err_free;
+		}
 
 		tipc_node_read_lock(node);
 		link = node->links[bearer_id].link;
 		if (!link) {
 			tipc_node_read_unlock(node);
-			nlmsg_free(msg.skb);
+			err = -EINVAL;
-			return -EINVAL;
+			goto err_free;
 		}
 
 		err = __tipc_nl_add_link(net, &msg, link, 0);
 		tipc_node_read_unlock(node);
-		if (err) {
+		if (err)
-			nlmsg_free(msg.skb);
+			goto err_free;
-			return err;
-		}
 	}
 
 	return genlmsg_reply(msg.skb, info);
+
+err_free:
+	nlmsg_free(msg.skb);
+	return err;
 }
 
 int tipc_nl_node_reset_link_stats(struct sk_buff *skb, struct genl_info *info)