From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick McHardy Subject: Re: rare bad TCP checksum with 2.6.19? Date: Tue, 16 Jan 2007 13:15:26 +0100 Message-ID: <45ACC1DE.6090708@trash.net> References: <45AB82F1.9000409@tls.msk.ru> <20070115201001.GA9510@gondor.apana.org.au> <45ABF620.3070405@tls.msk.ru> <20070116032739.GA12746@gondor.apana.org.au> <20070116033849.GA12856@gondor.apana.org.au> <45AC8813.9000204@tls.msk.ru> <20070116115053.GA16529@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: Michael Tokarev , netdev@vger.kernel.org Return-path: Received: from stinky.trash.net ([213.144.137.162]:49506 "EHLO stinky.trash.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750896AbXAPMPb (ORCPT ); Tue, 16 Jan 2007 07:15:31 -0500 To: Herbert Xu In-Reply-To: <20070116115053.GA16529@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Herbert Xu wrote: > On Tue, Jan 16, 2007 at 11:08:51AM +0300, Michael Tokarev wrote: > >>Ok. Here's another trace, from that remote network that triggers >>this thing more-or-less reliable (every 2nd transfer at least) -- >>http://www.corpit.ru/mjt/bh-bad-cksum-dmp.bin . It's a full session >>between 216.168.29.244 - the requesting/receiving side -- and >>81.13.94.6 -- our sending side (the file being transferred is some >>trojan horse I found on a friend's PC, so be careful ;) > > > I'll have a look at this tomorrow. > > Since you're certain that this is being seen on the wire, one > possibility is that we've got a bug somewhere that's zeroing > skb->ip_summed on a packet with a partial checksum. > > One potential spot where this could happen is netfilter. > Patrick, do you know of any recent changes (this is happening > with 2.6.19) that might cause this? The incremental HW checksum update stuff went in 2.6.19, so thats a prime suspect. Can't see where this could be happening though. Michael, how exactly is netfilter involved in your setup?