Re: WARNING: at net/ipv4/netfilter/nf_nat_standalone.c:89 nf_nat_fn+0x33/0x155()

[Patrick McHardy <kaber@trash.net>]

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Patrick McHardy wrote:
> Patrick McHardy wrote:
>> Nir Tzachar wrote:
>>> Hello.
>>>
>>> The following warning is reproducible with the code below on 2.6.25.6,
>>> which uses sendmsg on a udp socket using two iovecs:
>>>
>>> ....
>>> And I always get  the following warning twice:
>>>
>>> [ 6658.338116] ------------[ cut here ]------------
>>> [ 6658.338121] WARNING: at net/ipv4/netfilter/nf_nat_standalone.c:89
>>> nf_nat_fn+0x33/0x155()
>>
>> Thanks for the report. Does this patch fix it?
> 
> Actually, this can't be it. Let me look again.

Found it - we lost an ifdef during the transition to nf_conntrack
guarding an exception from defragmentation on loopback input.

This patch should fix the warning.

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diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
index 5a955c4..7eb0b61 100644
--- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
+++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
@@ -150,10 +150,12 @@ static unsigned int ipv4_conntrack_defrag(unsigned int hooknum,
 					  const struct net_device *out,
 					  int (*okfn)(struct sk_buff *))
 {
+#if !defined(CONFIG_NF_NAT) && !defined(CONFIG_NF_NAT_MODULE)
 	/* Previously seen (loopback)?  Ignore.  Do this before
 	   fragment check. */
 	if (skb->nfct)
 		return NF_ACCEPT;
+#endif
 
 	/* Gather fragments. */
 	if (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) {