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=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL 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 6021BC4363D for ; Fri, 25 Sep 2020 12:23:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E0EF4221EC for ; Fri, 25 Sep 2020 12:23:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="RaEYAZyM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728349AbgIYMXA (ORCPT ); Fri, 25 Sep 2020 08:23:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34250 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727248AbgIYMXA (ORCPT ); Fri, 25 Sep 2020 08:23:00 -0400 Received: from mail-qt1-x842.google.com (mail-qt1-x842.google.com [IPv6:2607:f8b0:4864:20::842]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 215D3C0613CE for ; Fri, 25 Sep 2020 05:23:00 -0700 (PDT) Received: by mail-qt1-x842.google.com with SMTP id e7so1610574qtj.11 for ; Fri, 25 Sep 2020 05:23:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=JiwHunS73dKhzMvuruWEdSZBTGiMntQmhlw2d9kKF/g=; b=RaEYAZyMGMIoGSW2BGdldXQO3drMp78uAOUNdZWmtOvAmvrNMB83DkVs1sU+EdK+vX jt/vAtjXKdHeGQxzML0VKsdyTahxAvwVtqnmJ9AZ/xT3FucZJtrqt/WtXImbKJnFuUK2 Gk6yAT0apPA+SN1McyqgpGm5FtNhaQgMXuHZh1JVR5iPuPrfgSv9zRVY2gJFZdY9N0Lc n9LTpqZzss8dC5ECoDAP8f+jnuuMzR3EOUqC9VUE5zhNh/TgwO7cIjqUxLREgH+i8VMo n4iTygX1f89Hywqi/5v37JQUzNjH8tcq84PP0oHrIj/etA5mwcTtjGBAgWUdmh7h6a4u r41g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=JiwHunS73dKhzMvuruWEdSZBTGiMntQmhlw2d9kKF/g=; b=Fpoep27Tz/Ej8QaZGA7igDp5G76hS7XaLVrgKyKM02JybLZii60ZQQwP2eVDti+BSo ZmDlPgtsrMm3GzUePjbRE9WA3rt6Y6k1j5rWwiAc9ukNtfwZA9qcASU6NLmDmkjNDM1+ eNnsbUFZhP4BWGH4gsp81QuBKl+BgUBV55eu2Sa4JVDl8tgCi9OFPmmuq+l93hdYNyew eg+5v4spFzqVT4weho/z9Zb9vhLwpcbqeO1Utn0hrSAxfspFyzY7bvOJCikKxonuwI76 Tlz3cMFV3iNgaa1aqDZQ72Kj+o8qwsaTZ5ZI4JGvy4S82375urwtX1kD43tvdY2k2BHM Pl6g== X-Gm-Message-State: AOAM532EKfJxvXPVsV50TM347Nn1HutyXM36IIZhNQE50IM12uNxoA0K LtdDQqzC+CfHJGspPCrq6DyuIwQSNDJR4Zq0TUSwpQ== X-Google-Smtp-Source: ABdhPJws0L/vacfbEcOsg6IKEchMzkUlgnq6GAfHWUrhCoS9hDF5oSiav2fAMewuaMCaa714dxufzQb39vW92/dZNeA= X-Received: by 2002:aed:26a7:: with SMTP id q36mr4018858qtd.57.1601036578995; Fri, 25 Sep 2020 05:22:58 -0700 (PDT) MIME-Version: 1.0 References: <00000000000052569205afa67426@google.com> <20200919110831.GD7462@zn.tnic> <20200921221336.GN5901@zn.tnic> <20200923090336.GD28545@zn.tnic> <20200923103431.GF28545@zn.tnic> In-Reply-To: From: Dmitry Vyukov Date: Fri, 25 Sep 2020 14:22:47 +0200 Message-ID: Subject: Re: general protection fault in perf_misc_flags To: Borislav Petkov Cc: Nick Desaulniers , Josh Poimboeuf , syzbot , Arnaldo Carvalho de Melo , Alexander Shishkin , "H. Peter Anvin" , Jiri Olsa , LKML , Mark Rutland , Ingo Molnar , Namhyung Kim , Peter Zijlstra , syzkaller-bugs , Thomas Gleixner , "the arch/x86 maintainers" , clang-built-linux Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 23, 2020 at 5:20 PM Dmitry Vyukov wrote: > > On Wed, Sep 23, 2020 at 12:34 PM Borislav Petkov wrote: > > > > On Wed, Sep 23, 2020 at 11:24:48AM +0200, Dmitry Vyukov wrote: > > > 3. Run syzkaller locally with custom patches. > > > > Let's say I wanna build the kernel with clang-10 using your .config and > > run it in a vm locally. What are the steps in order to reproduce the > > same workload syzkaller runs in the guest on the GCE so that I can at > > least try get as close as possible to reproducing locally? > > It's a random fuzzing workload. You can get this workload by running > syzkaller locally: > https://github.com/google/syzkaller/blob/master/docs/linux/setup_ubuntu-host_qemu-vm_x86-64-kernel.md > > The exact clang compiler syzbot used is available here: > https://github.com/google/syzkaller/blob/master/docs/syzbot.md#crash-does-not-reproduce I've marked all other similar ones a dup of this one. Now you can see all manifestations on the dashboard: https://syzkaller.appspot.com/bug?extid=ce179bc99e64377c24bc Another possible debugging vector on this: The location of crashes does not seem to be completely random and evenly spread across kernel code. I think there are many more static branches (mm, net), but we have 3 crashes in vdso and 9 in paravirt code + these 6 crashes in perf_misc_flags which looks a bit like an outlier (?). What's special about paravirt/vdso?..