Re: ipt_SYNPROXY: kernel panic caused by nullpointer dereference

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Sun, Dec 08, 2013 at 04:52:31PM +0000, Patrick McHardy wrote:
> On Sun, Dec 08, 2013 at 11:01:46AM +0100, Pablo Neira Ayuso wrote:
> > On Sun, Dec 08, 2013 at 08:16:00AM +0100, Nicki P. wrote:
> > > hi,
> > > 
> > > when activating ipt_SYNPROXY with:
> > > iptables -t raw -A PREROUTING -p tcp -d 1.2.3.4 --dport 80 --tcp-flags
> > > SYN,ACK,RST,FIN SYN -j SYNPROXY
> > >
> > > and sending a SYN packet to port 80:
> > > hping3 -S -d 64 1.2.3.4 -p 80
> > > 
> > > I get kernel panic:
> > > http://goo.gl/L6dCz6
> > >
> > > I'm using kernel v3.12.2 and iptables v1.4.21. Am I doing something wrong,
> > > or is it a bug?
> > 
> > You have to run this from the INPUT/FORWARD chain, SYNPROXY needs the
> > routing information to work.
> 
> Let's fix that:
> 
> From e5b31e75df3c3f9629900016a95336c04165d13f Mon Sep 17 00:00:00 2001
> From: Patrick McHardy <kaber@trash.net>
> Date: Sun, 8 Dec 2013 16:49:36 +0000
> Subject: [PATCH] netfilter: SYNPROXY target: restrict to INPUT/FORWARD
> 
> Fix a crash in synproxy_send_tcp() when using the SYNPROXY target in the
> PREROUTING chain caused by missing routing information.

Applied, thanks Patrick!