From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8A62AC43387 for ; Fri, 4 Jan 2019 17:14:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 603D8218D3 for ; Fri, 4 Jan 2019 17:14:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728097AbfADROe (ORCPT ); Fri, 4 Jan 2019 12:14:34 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41288 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726256AbfADROd (ORCPT ); Fri, 4 Jan 2019 12:14:33 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id F201281DE2; Fri, 4 Jan 2019 17:14:32 +0000 (UTC) Received: from localhost (ovpn-200-16.brq.redhat.com [10.40.200.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 91CC8101F97D; Fri, 4 Jan 2019 17:14:29 +0000 (UTC) Date: Fri, 4 Jan 2019 18:14:24 +0100 From: Stefano Brivio To: Dmitry Vyukov Cc: Willem de Bruijn , Eric Dumazet , syzbot , David Miller , Alexey Kuznetsov , linux-kernel , Network Development , syzkaller-bugs , Hideaki YOSHIFUJI Subject: Re: kernel panic: stack is corrupted in udp4_lib_lookup2 Message-ID: <20190104181424.5ad4b1de@redhat.com> In-Reply-To: References: <000000000000513fb7057e8d7013@google.com> <20190103210743.6518841e@redhat.com> <20190103225404.66b0ec9f@redhat.com> <20190104115435.478b4b4a@redhat.com> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Fri, 04 Jan 2019 17:14:33 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 4 Jan 2019 12:05:04 +0100 Dmitry Vyukov wrote: > On Fri, Jan 4, 2019 at 11:54 AM Stefano Brivio wrote: > > > > On Fri, 4 Jan 2019 11:32:12 +0100 > > Dmitry Vyukov wrote: > > > > > On Thu, Jan 3, 2019 at 10:54 PM Stefano Brivio wrote: > > > > > > > > On Thu, 3 Jan 2019 15:15:06 -0600 > > > > Willem de Bruijn wrote: > > > > > > > > > syzbot generated stack traces with > > > > > > > > > > [ 183.517380] udpv6_err+0x46/0x60 > > > > > [ 183.520739] ? __udp6_lib_err+0x1890/0x1890 > > > > > [ 183.525054] gue6_err_proto_handler+0x199/0x280 > > > > > > > > Where? I can't find that in any logs linked from the dashboard at > > > > https://syzkaller.appspot.com/bug?extid=4ad25edc7a33e4ab91e0 :( > > > > > > Stefano, there are these 4 bugs reported that have similarly looking > > > reproducers involving udp sockets and that crash modes that looks like > > > stack corruption/overflow: > > > > > > https://syzkaller.appspot.com/bug?extid=14005fa30c9a07192934 > > > https://syzkaller.appspot.com/bug?extid=d14090007dc9ba5fa9b7 > > > https://syzkaller.appspot.com/bug?extid=137ed32ec9a6d5b0d5fe > > > https://syzkaller.appspot.com/bug?id=d5bc3e0c66d200d72216ab343a67c4327e4a3452 > > > > > > Are these the same bug as this? > > > > Judging from the reproducers for the first three, they seem to be. > > OK, then I will mark them as dups of this one. syzbot just finished the tests I requested and couldn't reproduce the first three issues with the fix I posted (fou6: Prevent unbounded recursion in GUE error handler). This should prove they are in fact the same issue. > > I > > guess I can trigger tests also for those by sending a (sharp)syz > > test ... e-mail with the patch to the Reported-by: addresses, right? > > Correct. > These should be on LKML, but as you noted you can just add the syzbot > email with tag to TO/CC. That email is available in the Reported-by > tag (and also shown on the dashboard). Okay, thanks for confirming. > > And the three reports you pointed out from the pile of corrupted > > reports also seem to match, others look unrelated. > > I've added these as tests: > > https://github.com/google/syzkaller/blob/master/pkg/report/testdata/linux/report/341 > https://github.com/google/syzkaller/blob/master/pkg/report/testdata/linux/report/342 > https://github.com/google/syzkaller/blob/master/pkg/report/testdata/linux/report/343 > https://github.com/google/syzkaller/blob/master/pkg/report/testdata/linux/report/344 > > Will try to figure out how to distinguish them from true corrupted > reports. Usually when Call Trace does not have any frames, it's a sign > of a corrupted report, and in other crashes we see the same report but > with a stack trace. But some stack-corruption-related reliably don't > have stack traces (not corrupted). But then some other > stack-corruption-related crashes do have stack traces, and for these > no stack trace again means a corrupted kernel output. Amusingly this > is one of the most complex parts of syzkaller. I'm not sure how complicated that would be, but what about some metric based on valid symbol names being reported? -- Stefano