[PATCH 3.16.y-ckt 064/254] netfilter: nf_log: account for size of NLMSG_DONE attribute

[Luis Henriques]

3.16.7-ckt2 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Florian Westphal <fw@xxxxxxxxx>

commit 9dfa1dfe4d5e5e66a991321ab08afe69759d797a upstream.

We currently neither account for the nlattr size, nor do we consider
the size of the trailing NLMSG_DONE when allocating nlmsg skb.

This can result in nflog to stop working, as __nfulnl_send() re-tries
sending forever if it failed to append NLMSG_DONE (which will never
work if buffer is not large enough).

Reported-by: Houcheng Lin <houcheng@xxxxxxxxx>
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
 net/netfilter/nfnetlink_log.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
index d292c8d286eb..ebff1ec79ea2 100644
--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -649,7 +649,8 @@ nfulnl_log_packet(struct net *net,
 		+ nla_total_size(sizeof(u_int32_t))	/* gid */
 		+ 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 nfulnl_msg_packet_timestamp))
+		+ nla_total_size(sizeof(struct nfgenmsg));	/* NLMSG_DONE */
 
 	if (in && skb_mac_header_was_set(skb)) {
 		size +=   nla_total_size(skb->dev->hard_header_len)
@@ -692,8 +693,7 @@ nfulnl_log_packet(struct net *net,
 		goto unlock_and_release;
 	}
 
-	if (inst->skb &&
-	    size > skb_tailroom(inst->skb) - sizeof(struct nfgenmsg)) {
+	if (inst->skb && size > skb_tailroom(inst->skb)) {
 		/* either the queue len is too high or we don't have
 		 * enough room in the skb left. flush to userspace. */
 		__nfulnl_flush(inst);
-- 
2.1.0

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