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=-6.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS 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 065D9C433E7 for ; Fri, 9 Oct 2020 01:42:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9459322257 for ; Fri, 9 Oct 2020 01:42:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730499AbgJIBmA (ORCPT ); Thu, 8 Oct 2020 21:42:00 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:38896 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727313AbgJIBmA (ORCPT ); Thu, 8 Oct 2020 21:42:00 -0400 Received: from callcc.thunk.org (pool-72-74-133-215.bstnma.fios.verizon.net [72.74.133.215]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 0991ffma023866 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 8 Oct 2020 21:41:42 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id D432B420107; Thu, 8 Oct 2020 21:41:40 -0400 (EDT) Date: Thu, 8 Oct 2020 21:41:40 -0400 From: "Theodore Y. Ts'o" To: "zhangyi (F)" Cc: linux-ext4@vger.kernel.org, jack@suse.com, adilger.kernel@dilger.ca Subject: Re: [PATCH v2 1/7] ext4: clear buffer verified flag if read meta block from disk Message-ID: <20201009014140.GA816148@mit.edu> References: <20200924073337.861472-1-yi.zhang@huawei.com> <20200924073337.861472-2-yi.zhang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200924073337.861472-2-yi.zhang@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Thu, Sep 24, 2020 at 03:33:31PM +0800, zhangyi (F) wrote: > The metadata buffer is no longer trusted after we read it from disk > again because it is not uptodate for some reasons (e.g. failed to write > back). Otherwise we may get below memory corruption problem in > ext4_ext_split()->memset() if we read stale data from the newly > allocated extent block on disk which has been failed to async write > out but miss verify again since the verified bit has already been set > on the buffer. > > [ 29.774674] BUG: unable to handle kernel paging request at ffff88841949d000 > ... > [ 29.783317] Oops: 0002 [#2] SMP > [ 29.784219] R10: 00000000000f4240 R11: 0000000000002e28 R12: ffff88842fa1c800 > [ 29.784627] CPU: 1 PID: 126 Comm: kworker/u4:3 Tainted: G D W > [ 29.785546] R13: ffffffff9cddcc20 R14: ffffffff9cddd420 R15: ffff88842fa1c2f8 > [ 29.786679] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),BIOS ?-20190727_0738364 > [ 29.787588] FS: 0000000000000000(0000) GS:ffff88842fa00000(0000) knlGS:0000000000000000 > [ 29.789288] Workqueue: writeback wb_workfn > [ 29.790319] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 29.790321] (flush-8:0) > [ 29.790844] CR2: 0000000000000008 CR3: 00000004234f2000 CR4: 00000000000006f0 > [ 29.791924] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 29.792839] RIP: 0010:__memset+0x24/0x30 > [ 29.793739] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 29.794256] Code: 90 90 90 90 90 90 0f 1f 44 00 00 49 89 f9 48 89 d1 83 e2 07 48 c1 e9 033 > [ 29.795161] Kernel panic - not syncing: Fatal exception in interrupt > ... > [ 29.808149] Call Trace: > [ 29.808475] ext4_ext_insert_extent+0x102e/0x1be0 > [ 29.809085] ext4_ext_map_blocks+0xa89/0x1bb0 > [ 29.809652] ext4_map_blocks+0x290/0x8a0 > [ 29.809085] ext4_ext_map_blocks+0xa89/0x1bb0 > [ 29.809652] ext4_map_blocks+0x290/0x8a0 > [ 29.810161] ext4_writepages+0xc85/0x17c0 > ... > > Fix this by clearing buffer's verified bit if we read meta block from > disk again. > > Signed-off-by: zhangyi (F) > Cc: stable@vger.kernel.org Thanks, applied. - Ted