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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A8CA9E776D4 for ; Tue, 3 Oct 2023 00:12:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237272AbjJCAMx (ORCPT ); Mon, 2 Oct 2023 20:12:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37460 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229595AbjJCAMx (ORCPT ); Mon, 2 Oct 2023 20:12:53 -0400 Received: from mail-ot1-x341.google.com (mail-ot1-x341.google.com [IPv6:2607:f8b0:4864:20::341]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 65E35A7 for ; Mon, 2 Oct 2023 17:12:50 -0700 (PDT) Received: by mail-ot1-x341.google.com with SMTP id 46e09a7af769-6c6591642f2so54582a34.1 for ; Mon, 02 Oct 2023 17:12:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20230601.gappssmtp.com; s=20230601; t=1696291969; x=1696896769; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:references:to:from :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=3ZYFOCnJg3JB+NMDyiBkV1Ci3jAh1uzwfMkuIhs6hs0=; b=ZxK+ppqIAwBoLU4Zrlxbxl99bJyWSPO4YXpbA+aA5+U6dM6VaTw63DAV7ypdcRALLK yBwp4EY5sxDocSj8s/C6z13uZXD3A09KH5mBLmmig3gV6XiG29EY/mB2Tf1PfFWxRSUR FoX8DYHyYO1FWJEzZC/67CVuBck8rz8XOvIjFo9SAm1AosXqQmPdB7nVsSZsBzJKPV3i v8vB26ygaMFeX9CQ5p4xdisvL+xmkVDrCap42GCGd2AfyEQo6GlFFwQrWKv78ZHFv/Nz lmla6ezeiAA8EGRBRUkUSKsVFQ/GJFfKq3Ctl140G0Vgwic81uR3FlsWTKJuBAhFENrQ BsKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696291969; x=1696896769; h=content-transfer-encoding:in-reply-to:references:to:from :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=3ZYFOCnJg3JB+NMDyiBkV1Ci3jAh1uzwfMkuIhs6hs0=; b=i+1l0zJEjGprhqnLP6kqjYR1r088swlaQXgQQZB95MBvUFXss5pzaD4YE/ZYEiIH87 bbjdKVWggh1zQtotmoLIaL4SZD54/Ur0NI+bHnVJyAwcIbJ/qWe8GAZ4tJsaIBTi4ycZ 0ikonlP8VXO8M6g8rsbbaa1bf6WMgaD2AfD8+LyoAMVcIn5PdvwOndtuCYi7hpxGlH1c MjWZJ7ZdyxeQ5/Y+JcPBXNhZy5v/wKoNZImSSwB+ygwBEGtlQm/TQYV3cdYP2dAmEIeg WSJGkRrYunG17GrKDKItvx6RGobprsP8fa8FxL2f9KN58Ya6vrFv3vNO8X6b4V4fvvBZ SzUA== X-Gm-Message-State: AOJu0YxNTPybi9ZDbaBTzZQ/FOFE9nOECPJkw65jHD7QK2kU44Fe0H1m m7a70CYWIfNkvvMrBAumjynaIg== X-Google-Smtp-Source: AGHT+IF9baUR9p6DAKFjII/kVTO/AjJMvz3lg30gHWN7cn7bssakhG73wKi092cOJs92S3iO0TpdEQ== X-Received: by 2002:a05:6358:c610:b0:147:eb87:3665 with SMTP id fd16-20020a056358c61000b00147eb873665mr10087049rwb.3.1696291969642; Mon, 02 Oct 2023 17:12:49 -0700 (PDT) Received: from [192.168.1.136] ([198.8.77.194]) by smtp.gmail.com with ESMTPSA id f17-20020aa782d1000000b0068bc6a75848sm71459pfn.156.2023.10.02.17.12.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 02 Oct 2023 17:12:48 -0700 (PDT) Message-ID: Date: Mon, 2 Oct 2023 18:12:47 -0600 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [io-uring?] BUG: unable to handle kernel NULL pointer dereference in __io_remove_buffers (2) Content-Language: en-US From: Jens Axboe To: syzbot , asml.silence@gmail.com, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com References: <000000000000af635c0606bcb889@google.com> <7567c27a-b5d0-41fc-a7e5-d65ed168b39c@kernel.dk> In-Reply-To: <7567c27a-b5d0-41fc-a7e5-d65ed168b39c@kernel.dk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 10/2/23 10:43 AM, Jens Axboe wrote: > On 10/2/23 8:38 AM, syzbot wrote: >> Hello, >> >> syzbot found the following issue on: >> >> HEAD commit: ec8c298121e3 Merge tag 'x86-urgent-2023-10-01' of git://gi.. >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=16ef0ed6680000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=3be743fa9361d5b0 >> dashboard link: https://syzkaller.appspot.com/bug?extid=2113e61b8848fa7951d8 >> compiler: arm-linux-gnueabi-gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 >> userspace arch: arm > > I tried the syz repro in the console output, but can't trigger it. It > also makes very little sense to me... For when there is a reproducer, > the below would perhaps shed some light on it. We have bl->is_mapped == > 1, yet bl->buf_ring is NULL. Probably some artifact of 32-bit arm? I think this is 32-bit and highmem... The page being mapped into the kernel is a highmem page, and this won't really fly with having a permanent ->buf_ring address which we get from page_address(). -- Jens Axboe