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=-7.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 03481C433E0 for ; Wed, 10 Jun 2020 11:24:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C70AF204EA for ; Wed, 10 Jun 2020 11:24:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728450AbgFJLYE (ORCPT ); Wed, 10 Jun 2020 07:24:04 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:54116 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728322AbgFJLYE (ORCPT ); Wed, 10 Jun 2020 07:24:04 -0400 Received: from fsav401.sakura.ne.jp (fsav401.sakura.ne.jp [133.242.250.100]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 05ABNb8c049454; Wed, 10 Jun 2020 20:23:38 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav401.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav401.sakura.ne.jp); Wed, 10 Jun 2020 20:23:37 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav401.sakura.ne.jp) Received: from [192.168.1.9] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 05ABNWVG049156 (version=TLSv1.2 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Wed, 10 Jun 2020 20:23:37 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Subject: Re: general protection fault in proc_kill_sb To: viro@zeniv.linux.org.uk References: <0000000000002d7ca605a7b8b1c5@google.com> From: Tetsuo Handa Cc: syzbot , adobriyan@gmail.com, ebiederm@xmission.com, gladkov.alexey@gmail.com, keescook@chromium.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Message-ID: <10cd85a7-2958-57a8-aa7e-0075194fc788@I-love.SAKURA.ne.jp> Date: Wed, 10 Jun 2020 20:23:33 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <0000000000002d7ca605a7b8b1c5@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 2020/06/10 19:56, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: 7ae77150 Merge tag 'powerpc-5.8-1' of git://git.kernel.org.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=16e12212100000 > kernel config: https://syzkaller.appspot.com/x/.config?x=d195fe572fb15312 > dashboard link: https://syzkaller.appspot.com/bug?extid=4abac52934a48af5ff19 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > Unfortunately, I don't have any reproducer for this crash yet. The report says proc_sb_info(sb) == NULL at proc_kill_sb() which was called via fs->kill_sb(s) from deactivate_locked_super(). The console log says that memory allocation for proc_sb_info(sb) failed due to memory allocation fault injection. [ 1492.052802][ T6840] FAULT_INJECTION: forcing a failure. [ 1492.052802][ T6840] name failslab, interval 1, probability 0, space 0, times 0 [ 1492.077153][ T6840] CPU: 0 PID: 6840 Comm: syz-executor.2 Not tainted 5.7.0-syzkaller #0 [ 1492.085449][ T6840] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 1492.095511][ T6840] Call Trace: [ 1492.098811][ T6840] dump_stack+0x188/0x20d [ 1492.103157][ T6840] should_fail.cold+0x5/0xa [ 1492.107686][ T6840] ? fault_create_debugfs_attr+0x140/0x140 [ 1492.107721][ T6840] ? idr_replace+0xee/0x160 [ 1492.127210][ T6840] should_failslab+0x5/0xf [ 1492.131638][ T6840] kmem_cache_alloc_trace+0x2d0/0x7d0 [ 1492.137020][ T6840] ? up_write+0x148/0x470 [ 1492.141367][ T6840] proc_fill_super+0x79/0x5c0 [ 1492.146052][ T6840] ? proc_parse_param+0x8a0/0x8a0 [ 1492.151092][ T6840] vfs_get_super+0x12e/0x2d0 [ 1492.155694][ T6840] vfs_get_tree+0x89/0x2f0 [ 1492.160126][ T6840] do_mount+0x1306/0x1b40 [ 1492.164467][ T6840] ? copy_mount_string+0x40/0x40 [ 1492.169411][ T6840] ? __might_fault+0x190/0x1d0 [ 1492.174188][ T6840] ? _copy_from_user+0x13c/0x1a0 [ 1492.179138][ T6840] ? memdup_user+0x7c/0xd0 [ 1492.183575][ T6840] __x64_sys_mount+0x18f/0x230 [ 1492.188351][ T6840] do_syscall_64+0xf6/0x7d0 [ 1492.192861][ T6840] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 1492.198759][ T6840] RIP: 0033:0x45ca69 That is, proc_kill_sb() was assuming "s->s_fs_info = fs_info;" is always called from proc_fill_super() which is called via fill_super(sb, fc); from vfs_get_super().