netfilter: nfnetlink_log: account for netlink header size

This is a followup to an old bug fix: NLMSG_DONE needs to account
for the netlink header size, not just the attribute size.

This can result in a WARN splat + drop of the netlink message,
but other than this there are no ill effects.

Fixes: 9dfa1df ("netfilter: nf_log: account for size of NLMSG_DONE attribute")
Reported-by: Yiming Qian <yimingqian591@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Author: Florian Westphal

net/netfilter/nfnetlink_log.c

@@ -726,7 +726,7 @@ nfulnl_log_packet(struct net *net,
 		+ nla_total_size(plen)			/* prefix */
 		+ nla_total_size(sizeof(struct nfulnl_msg_packet_hw))
 		+ nla_total_size(sizeof(struct nfulnl_msg_packet_timestamp))
-		+ nla_total_size(sizeof(struct nfgenmsg));	/* NLMSG_DONE */
+		+ nlmsg_total_size(sizeof(struct nfgenmsg));	/* NLMSG_DONE */
 
 	if (in && skb_mac_header_was_set(skb)) {
 		size += nla_total_size(skb->dev->hard_header_len)