[PATCH 3.10 43/70] netfilter: nf_log: account for size of NLMSG_DONE attribute

Greg Kroah-Hartman
2014-11-19T21:19:38Z

From: Florian Westphal <fw@strlen.de>

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@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/netfilter/nfnetlink_log.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -647,7 +647,8 @@ 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)
@@ -690,8 +691,7 @@ 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);