From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754360AbaFYDvl (ORCPT ); Tue, 24 Jun 2014 23:51:41 -0400 Received: from mail-ig0-f175.google.com ([209.85.213.175]:47560 "EHLO mail-ig0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752599AbaFYDvj (ORCPT ); Tue, 24 Jun 2014 23:51:39 -0400 MIME-Version: 1.0 In-Reply-To: References: <20140616234254.GA15332@redhat.com> <20140623234759.GA19138@redhat.com> <20140624.172616.757600677169858458.davem@davemloft.net> Date: Tue, 24 Jun 2014 20:51:39 -0700 Message-ID: Subject: Re: [GIT] Networking From: Tom Herbert To: David Miller Cc: torvalds@linux-foundation.org, davej@redhat.com, Andrew Morton , Linux Netdev List , LKML Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I believe in the no scatter-gather case of skb_segment is not set correctly. Will post a patch momentarily. On Tue, Jun 24, 2014 at 8:05 PM, Tom Herbert wrote: >> tcp_gso_segment() makes sure that the headers are reachable in the linear >> area with the pskb_may_pull(skb, sizeof(*th)) call, and gso_make_checksum() >> is only working with the area up to SKB_GSO_CB()->csum_start which should >> be within this area for sure. >> > Seems likely that csum_start is not properly initialized in this path. > I am thinking that this may have happened in GRO path on a checksum > error where CHECKSUM_PARTIAL (and hence csum) is not set. That would > explain the infrequency of the occurrence, and also previously not > setting csum would have just resulted in sending a corrupted packet > not a crash. > >> Well, that's the precondition we seem to be relying upon, I suppose an >> assert is in order. > > Assert on SKB_GSO_CB()->csum_start == 0 would confirm my suspicion.