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=-12.3 required=3.0 tests=BAYES_00, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 6C324C433F5 for ; Wed, 22 Sep 2021 13:21:22 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6292B61153 for ; Wed, 22 Sep 2021 13:21:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 6292B61153 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=139.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4HDzTD06CDz2yPK for ; Wed, 22 Sep 2021 23:21:20 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=139.com (client-ip=120.232.169.114; helo=n169-114.mail.139.com; envelope-from=cgxu519@139.com; receiver=) Received: from n169-114.mail.139.com (n169-114.mail.139.com [120.232.169.114]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4HDzT56Tbpz2xWx for ; Wed, 22 Sep 2021 23:21:10 +1000 (AEST) X-RM-TagInfo: emlType=0 X-RM-SPAM: X-RM-SPAM-FLAG: 00000000 Received: from [192.168.255.10] (unknown[113.108.77.67]) by rmsmtp-lg-appmail-39-12053 (RichMail) with SMTP id 2f15614b2db0269-70997; Wed, 22 Sep 2021 21:20:51 +0800 (CST) X-RM-TRANSID: 2f15614b2db0269-70997 Message-ID: <314324e7-02d7-dc43-b270-fb8117953549@139.com> Date: Wed, 22 Sep 2021 21:20:50 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.1.1 From: Chengguang Xu Subject: Re: [PATCH v3] ovl: fix null pointer when filesystemdoesn'tsupportdirect IO To: Huang Jianan , linux-unionfs@vger.kernel.org, miklos@szeredi.hu, linux-erofs@lists.ozlabs.org, xiang@kernel.org, chao@kernel.org References: <9ef909de-1854-b4be-d272-2b4cda52329f@oppo.com> <20210922072326.3538-1-huangjianan@oppo.com> <919e929d-6af7-b729-9fd2-954cd1e52999@oppo.com> In-Reply-To: <919e929d-6af7-b729-9fd2-954cd1e52999@oppo.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-BeenThere: linux-erofs@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development of Linux EROFS file system List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: zhangshiming@oppo.com, linux-kernel@vger.kernel.org, cgxu519@mykernel.net, yh@oppo.com, guanyuwei@oppo.com, linux-fsdevel@vger.kernel.org, guoweichao@oppo.com Errors-To: linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Sender: "Linux-erofs" 在 2021/9/22 16:24, Huang Jianan 写道: > > > 在 2021/9/22 16:06, Chengguang Xu 写道: >> 在 2021/9/22 15:23, Huang Jianan 写道: >>> From: Huang Jianan >>> >>> At present, overlayfs provides overlayfs inode to users. Overlayfs >>> inode provides ovl_aops with noop_direct_IO to avoid open failure >>> with O_DIRECT. But some compressed filesystems, such as erofs and >>> squashfs, don't support direct_IO. >>> >>> Users who use f_mapping->a_ops->direct_IO to check O_DIRECT support, >>> will read file through this way. This will cause overlayfs to access >>> a non-existent direct_IO function and cause panic due to null pointer: >> >> I just looked around the code more closely, in open_with_fake_path(), >> >> do_dentry_open() has already checked O_DIRECT open flag and >> a_ops->direct_IO of underlying real address_space. >> >> Am I missing something? >> >> > > It seems that loop_update_dio will set lo->use_dio after open file > without set O_DIRECT. > loop_update_dio will check f_mapping->a_ops->direct_IO but it deal > with ovl_aops with > noop _direct_IO. > > So I think we still need a new aops? It means we should only set ->direct_IO for overlayfs inodes whose underlying fs has DIRECT IO ability. Hi Miklos, Is it right solution for this kind of issue? What do you think? Thanks, Chengguang > > Thanks, > Jianan > >> Thanks, >> >> Chengguang >> >> >>> >>> Kernel panic - not syncing: CFI failure (target: 0x0) >>> CPU: 6 PID: 247 Comm: loop0 >>> Call Trace: >>> panic+0x188/0x45c >>> __cfi_slowpath+0x0/0x254 >>> __cfi_slowpath+0x200/0x254 >>> generic_file_read_iter+0x14c/0x150 >>> vfs_iocb_iter_read+0xac/0x164 >>> ovl_read_iter+0x13c/0x2fc >>> lo_rw_aio+0x2bc/0x458 >>> loop_queue_work+0x4a4/0xbc0 >>> kthread_worker_fn+0xf8/0x1d0 >>> loop_kthread_worker_fn+0x24/0x38 >>> kthread+0x29c/0x310 >>> ret_from_fork+0x10/0x30 >>> >>> The filesystem may only support direct_IO for some file types. For >>> example, erofs supports direct_IO for uncompressed files. So return >>> -EINVAL when the file doesn't support direct_IO to fix this problem. >>> >>> Fixes: 5b910bd615ba ("ovl: fix GPF in swapfile_activate of file from >>> overlayfs over xfs") >>> Signed-off-by: Huang Jianan >>> --- >>> change since v2: >>> - Return error in ovl_open directly. (Chengguang Xu) >>> >>> Change since v1: >>> - Return error to user rather than fall back to buffered io. >>> (Chengguang Xu) >>> >>> fs/overlayfs/file.c | 4 ++++ >>> 1 file changed, 4 insertions(+) >>> >>> diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c >>> index d081faa55e83..a0c99ea35daf 100644 >>> --- a/fs/overlayfs/file.c >>> +++ b/fs/overlayfs/file.c >>> @@ -157,6 +157,10 @@ static int ovl_open(struct inode *inode, struct >>> file *file) >>> if (IS_ERR(realfile)) >>> return PTR_ERR(realfile); >>> + if ((f->f_flags & O_DIRECT) && (!realfile->f_mapping->a_ops || >>> + !realfile->f_mapping->a_ops->direct_IO)) >>> + return -EINVAL; >>> + >>> file->private_data = realfile; >>> return 0; >> > 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=-12.3 required=3.0 tests=BAYES_00, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, 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 94C18C433F5 for ; Wed, 22 Sep 2021 13:30:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 78E28611B0 for ; Wed, 22 Sep 2021 13:30:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232139AbhIVNcA (ORCPT ); Wed, 22 Sep 2021 09:32:00 -0400 Received: from n169-114.mail.139.com ([120.232.169.114]:14867 "EHLO n169-114.mail.139.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231864AbhIVNcA (ORCPT ); Wed, 22 Sep 2021 09:32:00 -0400 X-Greylist: delayed 575 seconds by postgrey-1.27 at vger.kernel.org; Wed, 22 Sep 2021 09:31:57 EDT X-RM-TagInfo: emlType=0 X-RM-SPAM: X-RM-SPAM-FLAG: 00000000 Received: from [192.168.255.10] (unknown[113.108.77.67]) by rmsmtp-lg-appmail-39-12053 (RichMail) with SMTP id 2f15614b2db0269-70997; Wed, 22 Sep 2021 21:20:51 +0800 (CST) X-RM-TRANSID: 2f15614b2db0269-70997 Message-ID: <314324e7-02d7-dc43-b270-fb8117953549@139.com> Date: Wed, 22 Sep 2021 21:20:50 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.1.1 From: Chengguang Xu Subject: Re: [PATCH v3] ovl: fix null pointer when filesystemdoesn'tsupportdirect IO To: Huang Jianan , linux-unionfs@vger.kernel.org, miklos@szeredi.hu, linux-erofs@lists.ozlabs.org, xiang@kernel.org, chao@kernel.org Cc: guoweichao@oppo.com, yh@oppo.com, zhangshiming@oppo.com, guanyuwei@oppo.com, jnhuang95@gmail.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, cgxu519@mykernel.net References: <9ef909de-1854-b4be-d272-2b4cda52329f@oppo.com> <20210922072326.3538-1-huangjianan@oppo.com> <919e929d-6af7-b729-9fd2-954cd1e52999@oppo.com> In-Reply-To: <919e929d-6af7-b729-9fd2-954cd1e52999@oppo.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org 在 2021/9/22 16:24, Huang Jianan 写道: > > > 在 2021/9/22 16:06, Chengguang Xu 写道: >> 在 2021/9/22 15:23, Huang Jianan 写道: >>> From: Huang Jianan >>> >>> At present, overlayfs provides overlayfs inode to users. Overlayfs >>> inode provides ovl_aops with noop_direct_IO to avoid open failure >>> with O_DIRECT. But some compressed filesystems, such as erofs and >>> squashfs, don't support direct_IO. >>> >>> Users who use f_mapping->a_ops->direct_IO to check O_DIRECT support, >>> will read file through this way. This will cause overlayfs to access >>> a non-existent direct_IO function and cause panic due to null pointer: >> >> I just looked around the code more closely, in open_with_fake_path(), >> >> do_dentry_open() has already checked O_DIRECT open flag and >> a_ops->direct_IO of underlying real address_space. >> >> Am I missing something? >> >> > > It seems that loop_update_dio will set lo->use_dio after open file > without set O_DIRECT. > loop_update_dio will check f_mapping->a_ops->direct_IO but it deal > with ovl_aops with > noop _direct_IO. > > So I think we still need a new aops? It means we should only set ->direct_IO for overlayfs inodes whose underlying fs has DIRECT IO ability. Hi Miklos, Is it right solution for this kind of issue? What do you think? Thanks, Chengguang > > Thanks, > Jianan > >> Thanks, >> >> Chengguang >> >> >>> >>> Kernel panic - not syncing: CFI failure (target: 0x0) >>> CPU: 6 PID: 247 Comm: loop0 >>> Call Trace: >>> panic+0x188/0x45c >>> __cfi_slowpath+0x0/0x254 >>> __cfi_slowpath+0x200/0x254 >>> generic_file_read_iter+0x14c/0x150 >>> vfs_iocb_iter_read+0xac/0x164 >>> ovl_read_iter+0x13c/0x2fc >>> lo_rw_aio+0x2bc/0x458 >>> loop_queue_work+0x4a4/0xbc0 >>> kthread_worker_fn+0xf8/0x1d0 >>> loop_kthread_worker_fn+0x24/0x38 >>> kthread+0x29c/0x310 >>> ret_from_fork+0x10/0x30 >>> >>> The filesystem may only support direct_IO for some file types. For >>> example, erofs supports direct_IO for uncompressed files. So return >>> -EINVAL when the file doesn't support direct_IO to fix this problem. >>> >>> Fixes: 5b910bd615ba ("ovl: fix GPF in swapfile_activate of file from >>> overlayfs over xfs") >>> Signed-off-by: Huang Jianan >>> --- >>> change since v2: >>> - Return error in ovl_open directly. (Chengguang Xu) >>> >>> Change since v1: >>> - Return error to user rather than fall back to buffered io. >>> (Chengguang Xu) >>> >>> fs/overlayfs/file.c | 4 ++++ >>> 1 file changed, 4 insertions(+) >>> >>> diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c >>> index d081faa55e83..a0c99ea35daf 100644 >>> --- a/fs/overlayfs/file.c >>> +++ b/fs/overlayfs/file.c >>> @@ -157,6 +157,10 @@ static int ovl_open(struct inode *inode, struct >>> file *file) >>> if (IS_ERR(realfile)) >>> return PTR_ERR(realfile); >>> + if ((f->f_flags & O_DIRECT) && (!realfile->f_mapping->a_ops || >>> + !realfile->f_mapping->a_ops->direct_IO)) >>> + return -EINVAL; >>> + >>> file->private_data = realfile; >>> return 0; >> >