drop_monitor: consider inserted data in genlmsg_end

commit 3b48ab22 upstream.

Final nlmsg_len field update must reflect inserted net_dm_drop_point
data.

This patch depends on previous patch:
"drop_monitor: add missing call to genlmsg_end"
Signed-off-by: Reiter Wolfgang <wr0112358@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>

net/core/drop_monitor.c

@@ -107,7 +107,6 @@ static struct sk_buff *reset_per_cpu_data(struct per_cpu_dm_data *data)
 	}
 	msg = nla_data(nla);
 	memset(msg, 0, al);
-	genlmsg_end(skb, msg_header);
 	goto out;
 
 err:
@@ -117,6 +116,13 @@ static struct sk_buff *reset_per_cpu_data(struct per_cpu_dm_data *data)
 	swap(data->skb, skb);
 	spin_unlock_irqrestore(&data->lock, flags);
 
+	if (skb) {
+		struct nlmsghdr *nlh = (struct nlmsghdr *)skb->data;
+		struct genlmsghdr *gnlh = (struct genlmsghdr *)nlmsg_data(nlh);
+
+		genlmsg_end(skb, genlmsg_data(gnlh));
+	}
+
 	return skb;
 }