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=-6.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 7286AC4320A for ; Wed, 18 Aug 2021 08:55:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 547556024A for ; Wed, 18 Aug 2021 08:55:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229944AbhHRI4B (ORCPT ); Wed, 18 Aug 2021 04:56:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229820AbhHRIz7 (ORCPT ); Wed, 18 Aug 2021 04:55:59 -0400 Received: from mail-lj1-x229.google.com (mail-lj1-x229.google.com [IPv6:2a00:1450:4864:20::229]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 14241C061764; Wed, 18 Aug 2021 01:55:23 -0700 (PDT) Received: by mail-lj1-x229.google.com with SMTP id x7so3708667ljn.10; Wed, 18 Aug 2021 01:55:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language:content-transfer-encoding; bh=PyuHTiYtcp7PenUOgX16JRdXO479FYx66sP5cfTDtJ8=; b=bFhAKTFYhRq6nSBU53V7nBfYhXxkjiAhCqJps2SBtRGMCJIXp+7lU6McxX8loQ6meE fSG/FM3TmRbrP/b8JPftQvirvT0vqmE8IBifTejnoi6fVmyDgoVZJi0A2nL7TEJ5ep6U o2VSz0DNti8zycJniW8NTFPj0oSHwn9/KbdCQon5p3dgkjGpfZjfSf9d8VaQbCgzW7AF xcA2d+ms1Dm0JAK5Ztk4Qxii2GLc9+YyZSyRDLbM8q8GIfUWYUD2PlJCGYGdRSa9U/SY wlL63UXYJiyw80MiPemF3cVUtFHjQpfvfBbn2auULEHwWpm/C6cbpNM1CHQtc6q3bxgN f9Kw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=PyuHTiYtcp7PenUOgX16JRdXO479FYx66sP5cfTDtJ8=; b=BlTUqSkQpk/9Fc47ea6C798OCLe1seYD/jZuiUYoaIcewbU9eVq+YKfq8kf29xRcNE JphiwLv128X5VInOYG/JrVTe10GQI4cTRpAYCJrmV+5k1pq138UDMOcg13YiufutSwOA 1Q0GyJVa7ZFRf8SL7xFbYVTE6STzm3iAwb7/1d7MW6PpxMisiViO9xOubqbjmmjsGs6L oOudwkfap5IAyMvJPpevV7J8S+M+z/B/bUZEcmOSrDTX8lS/IoruXQRGCg7wNtS4wIeK 3OfjpnB/SqFODHYvHJ3D6sKqDmMlc3bgYQ6qy757FW1qJs/FLyoQhP47p1o88C9w2tA+ 6XFg== X-Gm-Message-State: AOAM532llg9xnFPxgXrmwrkGueuvVGythGXIiMGeW7xcPGt2ghsBjfly Iuu5pqG0kN2Qxo0SqjYdM6g= X-Google-Smtp-Source: ABdhPJzBpe3DARPr+h0Pu2Yu7QwdF+94FYfIVaP5pXL2ykMkVckZmxUEm9OoslOsTrhEkgEvNsI3Fg== X-Received: by 2002:a2e:b611:: with SMTP id r17mr7101788ljn.10.1629276921412; Wed, 18 Aug 2021 01:55:21 -0700 (PDT) Received: from localhost.localdomain ([46.61.204.60]) by smtp.gmail.com with ESMTPSA id g5sm432730lfe.174.2021.08.18.01.55.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 18 Aug 2021 01:55:20 -0700 (PDT) Subject: Re: [syzbot] KFENCE: use-after-free in kvm_fastop_exception To: Matthieu Baerts , syzbot , davem@davemloft.net, johan.hedberg@gmail.com, kuba@kernel.org, linux-bluetooth@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, luiz.dentz@gmail.com, marcel@holtmann.org, mathew.j.martineau@linux.intel.com, netdev@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk References: <00000000000012030e05c9c8bc85@google.com> <58cef9e0-69de-efdb-4035-7c1ed3d23132@tessares.net> <6736a510-20a1-9fb5-caf4-86334cabbbb6@gmail.com> <32aeb66e-d4f0-26b5-a140-4477bb87067f@tessares.net> From: Pavel Skripkin Message-ID: <3a8dd8db-61d6-603e-b270-5faf1be02c6b@gmail.com> Date: Wed, 18 Aug 2021 11:55:19 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <32aeb66e-d4f0-26b5-a140-4477bb87067f@tessares.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/18/21 11:21 AM, Matthieu Baerts wrote: > Hi Pavel, > [snip] >>> >>> I'm pretty sure the commit c4512c63b119 ("mptcp: fix 'masking a bool' >>> warning") doesn't introduce the reported bug. This minor fix is specific >>> to MPTCP which doesn't seem to be used here. >>> >>> I'm not sure how I can tell syzbot this is a false positive. >>> >> >> >> looks like it's fs/namei bug. Similar reports: >> >> https://syzkaller.appspot.com/bug?id=517fa734b92b7db404c409b924cf5c997640e324 >> >> >> https://syzkaller.appspot.com/bug?id=484483daf3652b40dae18531923aa9175d392a4d > > Thank you for having checked! > Should we mark them as "#syz dup" if you think they have the same root > cause? > I think, yes, but I want to receive feedback from fs people about this bug. There were huge updates last month, and, maybe, I am missing some details. Alloc/free calltrace is the same, but anyway, I want some confirmation to not close different bugs by mistake :) If these bugs really have same root case I will close them manually after fix posted. >> It's not false positive. I've suggested the fix here: >> https://groups.google.com/g/syzkaller-bugs/c/HE3c2fP5nic/m/1Yk17GBeAwAJ >> I am waiting for author comments about the fix :) >> >> But, yes, syzbot bisection is often wrong, so don't rely on it much :) > > Yes sorry, I wanted to say the bisection picked a wrong commit :) > > All good then if syzbot often blames the wrong modification :) > With regards, Pavel Skripkin