From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: kernel >= 4.0: crashes when using traceroute6 with isatap Date: Wed, 06 May 2015 15:42:38 -0700 Message-ID: <1430952158.14545.97.camel@edumazet-glaptop2.roam.corp.google.com> References: <1770409.aMESoOv08f@h2o.as.studentenwerk.mhn.de> <1430939400.14545.65.camel@edumazet-glaptop2.roam.corp.google.com> <2723870.nq54KKjWkm@h2o.as.studentenwerk.mhn.de> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Cong Wang , Vlad Yasevich , LKML , Hannes Frederic Sowa , Linux Kernel Network Developers To: Wolfgang Walter Return-path: In-Reply-To: <2723870.nq54KKjWkm@h2o.as.studentenwerk.mhn.de> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, 2015-05-07 at 00:04 +0200, Wolfgang Walter wrote: > Am Mittwoch, 6. Mai 2015, 12:10:00 schrieb Eric Dumazet: > > On Wed, 2015-05-06 at 11:15 -0700, Cong Wang wrote: > > > (Cc'ing netdev.) > > > > > > On Sat, May 2, 2015 at 5:29 AM, Wolfgang Walter wrote: > > > > Am Samstag, 2. Mai 2015, 02:16:36 schrieb Wolfgang Walter: > > > >> Hello, > > > >> > > > >> kernel 4.0 (and 4.0.1) crashes immediately when I use traceroute6 with > > > >> an > > > >> isatap-tunnel. > > > > > > > > I did some further tests. To trigger the crash you need > > > > > > > > * isatap-tunnel (probably any sit-tunnel will do it) > > > > * raw-socket > > > > * udp > > > > > > > > Using icmpv6 or tcp i.e. does not trigger it. > > > > > > Do you have a script to reproduce it? > > > > > > > > > Thanks for the bug report! > > > -- > > > > Please Wolfgang try to revert 32dce968dd987adfb0c00946d78dad9154f64759 > > ("ipv6: Allow for partial checksums on non-ufo packets") > > Indeed, that fixes the problem. Yes, setting skb->csum to 0 is clearly wrong for CHECKSUM_PARTIAL Would you try : diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 7fde1f265c90e90f16291e6c861b6e242111c25b..694ae630e1ca67e25ab1e5f6dd0b3597db3669b0 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1416,6 +1416,10 @@ alloc_new_skb: data += fragheaderlen; skb->transport_header = (skb->network_header + fragheaderlen); + if (csummode == CHECKSUM_PARTIAL) { + skb->csum_start = skb_transport_header(skb) - skb->head; + skb->csum_offset = offsetof(struct udphdr, check); + } if (fraggap) { skb->csum = skb_copy_and_csum_bits( skb_prev, maxfraglen,