Hello,
On Tue, 7 Jun 2011, Patrick McHardy wrote:
> On 29.05.2011 22:42, Julian Anastasov wrote:
> >
> > Fix crash in nf_nat_csum when mangling packets
> > in OUTPUT hook where skb->dev is not defined, it is set
> > later before POSTROUTING. Problem happens for CHECKSUM_NONE.
> > We can check device from rt but using CHECKSUM_PARTIAL
> > should be safe (skb_checksum_help).
>
> We don't call helpers in LOCAL_OUT, how can this happen?
I think, this happened with IPVS only in OUTPUT hook:
tcp_snat_handler -> ip_vs_ftp_out -> nf_nat_mangle_tcp_packet ->
nf_nat_csum. This is again PASV FTP via loopback.
> > diff -urp v2.6.39/linux/net/ipv4/netfilter/nf_nat_helper.c linux/net/ipv4/netfilter/nf_nat_helper.c
> > --- v2.6.39/linux/net/ipv4/netfilter/nf_nat_helper.c 2011-01-06 00:01:22.000000000 +0200
> > +++ linux/net/ipv4/netfilter/nf_nat_helper.c 2011-05-29 23:14:40.166245897 +0300
> > @@ -160,7 +160,7 @@ static void nf_nat_csum(struct sk_buff *
> >
> > if (skb->ip_summed != CHECKSUM_PARTIAL) {
> > if (!(rt->rt_flags & RTCF_LOCAL) &&
> > - skb->dev->features & NETIF_F_V4_CSUM) {
> > + (!skb->dev || skb->dev->features & NETIF_F_V4_CSUM)) {
> > skb->ip_summed = CHECKSUM_PARTIAL;
> > skb->csum_start = skb_headroom(skb) +
> > skb_network_offset(skb) +
> >
Regards
--
Julian Anastasov <ja@xxxxxx>
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