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netfilter: nf_log: release skbuff on nlmsg put failure

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The kernel should reserve enough room in the skb so that the DONE
message can always be appended.  However, in case of e.g. new attribute
erronously not being size-accounted for, __nfulnl_send() will still
try to put next nlmsg into this full skbuf, causing the skb to be stuck
forever and blocking delivery of further messages.

Fix issue by releasing skb immediately after nlmsg_put error and
WARN() so we can track down the cause of such size mismatch.

[ fw@strlen.de: add tailroom/len info to WARN ]

Signed-off-by: Houcheng Lin <houcheng@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Houcheng Lin 2014-10-23 10:36:08 +02:00 committed by Pablo Neira Ayuso
parent c1e7dc91ee
commit b51d3fa364
1 changed files with 8 additions and 9 deletions
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17
net/netfilter/nfnetlink_log.c
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@ -346,26 +346,25 @@ nfulnl_alloc_skb(struct net *net, u32 peer_portid, unsigned int inst_size,
return skb; return skb;
} }
static int static void
__nfulnl_send(struct nfulnl_instance *inst) __nfulnl_send(struct nfulnl_instance *inst)
{ {
int status = -1;
if (inst->qlen > 1) { if (inst->qlen > 1) {
struct nlmsghdr *nlh = nlmsg_put(inst->skb, 0, 0, struct nlmsghdr *nlh = nlmsg_put(inst->skb, 0, 0,
NLMSG_DONE, NLMSG_DONE,
sizeof(struct nfgenmsg), sizeof(struct nfgenmsg),
0); 0);
if (!nlh) if (WARN_ONCE(!nlh, "bad nlskb size: %u, tailroom %d\n",
inst->skb->len, skb_tailroom(inst->skb))) {
kfree_skb(inst->skb);
goto out; goto out;
}
} }
status = nfnetlink_unicast(inst->skb, inst->net, inst->peer_portid, nfnetlink_unicast(inst->skb, inst->net, inst->peer_portid,
MSG_DONTWAIT); MSG_DONTWAIT);
out:
inst->qlen = 0; inst->qlen = 0;
inst->skb = NULL; inst->skb = NULL;
out:
return status;
} }
static void static void