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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 3548EC2D0BF for ; Thu, 5 Dec 2019 13:20:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 10DD320675 for ; Thu, 5 Dec 2019 13:20:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729557AbfLENT6 (ORCPT ); Thu, 5 Dec 2019 08:19:58 -0500 Received: from www62.your-server.de ([213.133.104.62]:35820 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729240AbfLENT6 (ORCPT ); Thu, 5 Dec 2019 08:19:58 -0500 Received: from 29.249.197.178.dynamic.dsl-lte-bonding.lssmb00p-msn.res.cust.swisscom.ch ([178.197.249.29] helo=localhost) by www62.your-server.de with esmtpsa (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89_1) (envelope-from ) id 1icr2v-00019m-4m; Thu, 05 Dec 2019 14:19:53 +0100 Date: Thu, 5 Dec 2019 14:19:52 +0100 From: Daniel Borkmann To: Daniel Axtens Cc: Dmitry Vyukov , syzbot , kasan-dev , Andrii Nakryiko , Alexei Starovoitov , bpf , Martin KaFai Lau , LKML , netdev , Song Liu , syzkaller-bugs , Yonghong Song , Andrey Ryabinin Subject: Re: BUG: unable to handle kernel paging request in pcpu_alloc Message-ID: <20191205131952.GD29780@localhost.localdomain> References: <000000000000314c120598dc69bd@google.com> <877e3be6eu.fsf@dja-thinkpad.axtens.net> <20191205125900.GB29780@localhost.localdomain> <871rtiex4e.fsf@dja-thinkpad.axtens.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <871rtiex4e.fsf@dja-thinkpad.axtens.net> User-Agent: Mutt/1.12.1 (2019-06-15) X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.101.4/25654/Thu Dec 5 10:46:25 2019) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 06, 2019 at 12:10:41AM +1100, Daniel Axtens wrote: > Daniel Borkmann writes: > > On Thu, Dec 05, 2019 at 03:35:21PM +1100, Daniel Axtens wrote: > >> >> HEAD commit: 1ab75b2e Add linux-next specific files for 20191203 > >> >> git tree: linux-next > >> >> console output: https://syzkaller.appspot.com/x/log.txt?x=10edf2eae00000 > >> >> kernel config: https://syzkaller.appspot.com/x/.config?x=de1505c727f0ec20 > >> >> dashboard link: https://syzkaller.appspot.com/bug?extid=82e323920b78d54aaed5 > >> >> compiler: gcc (GCC) 9.0.0 20181231 (experimental) > >> >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=156ef061e00000 > >> >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11641edae00000 > >> >> > >> >> IMPORTANT: if you fix the bug, please add the following tag to the commit: > >> >> Reported-by: syzbot+82e323920b78d54aaed5@syzkaller.appspotmail.com > >> > > >> > +Daniel, is it the same as: > >> > https://syzkaller.appspot.com/bug?id=f6450554481c55c131cc23d581fbd8ea42e63e18 > >> > If so, is it possible to make KASAN detect this consistently with the > >> > same crash type so that syzbot does not report duplicates? > >> > >> It looks like both of these occur immediately after failure injection. I > >> think my assumption that I could ignore the chance of failures in the > >> per-cpu allocation path will have to be revisited. That's annoying. > >> > >> I'll try to spin something today but Andrey feel free to pip me at the > >> post again :) > >> > >> I'm not 100% confident to call them dups just yet, but I'm about 80% > >> confident that they are. > > > > Ok. Double checked BPF side yesterday night, but looks sane to me and the > > fault also hints into pcpu_alloc() rather than BPF code. Daniel, from your > > above reply, I read that you are aware of how the bisected commit would > > have caused the fault? > > Yes, this one is on me - I did not take into account the brutal > efficiency of the fault injector when implementing my KASAN support for > vmalloc areas. I have a fix, I'm just doing final tests now. Perfect, thanks a lot!