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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,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 72203C433DF for ; Fri, 5 Jun 2020 18:11:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 51806207ED for ; Fri, 5 Jun 2020 18:11:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="TOJoy37I" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728146AbgFESLP (ORCPT ); Fri, 5 Jun 2020 14:11:15 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:52808 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726077AbgFESLO (ORCPT ); Fri, 5 Jun 2020 14:11:14 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 055I8CQ5102490; Fri, 5 Jun 2020 18:10:59 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2020-01-29; bh=a4XaveQpAaQa2mw3il6Qi66Kdmgjqk/04IfyDbfuZOQ=; b=TOJoy37INOWoUNxh4EAkC3tJJh/ECSCuvtOhWAS4NSeZyCjRrCsD3Z6EetUvUSKmEpeZ E3ytfPKjbZvHXMkE1Swau4LvjbD5QlmLYz+FR3/6i34071X0mYTEReOpYGAdX4KGVbCp myCums3m3orFSmWW+bojM2PR10BZE0EX8efh9tHMtZg2v1HwZ+JhXz3bXXzUhdErnbFe IK3q+Ui7W47bNb+YTwqM4kpK2eT9tP5bLdgaroFCzxRztvvp+RtWr5v7XJhA2Mxft5F2 ozk92BhoV8J20fNyWVJGvnWMPaD/Qq3hMbyn5ImjbQFbYgh9MDypv9SYYQkDz196ksQX OA== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by userp2120.oracle.com with ESMTP id 31f926445u-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 05 Jun 2020 18:10:59 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 055I88MV181261; Fri, 5 Jun 2020 18:08:58 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3020.oracle.com with ESMTP id 31f928aagq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 05 Jun 2020 18:08:58 +0000 Received: from abhmp0016.oracle.com (abhmp0016.oracle.com [141.146.116.22]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 055I8tPQ026391; Fri, 5 Jun 2020 18:08:56 GMT Received: from kadam (/41.57.98.10) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 05 Jun 2020 11:08:54 -0700 Date: Fri, 5 Jun 2020 21:08:45 +0300 From: Dan Carpenter To: Jan Kara Cc: Jason Yan , Markus Elfring , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, hulkci@huawei.com, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org, Al Viro , Christoph Hellwig , Jens Axboe , Ming Lei Subject: Re: [PATCH v2] block: Fix use-after-free in blkdev_get() Message-ID: <20200605180845.GU30374@kadam> References: <88676ff2-cb7e-70ec-4421-ecf8318990b1@web.de> <5fa658bf-3028-9b5c-30cc-dbdef6bf8f7a@huawei.com> <20200605094353.GS30374@kadam> <20200605144236.GB13248@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200605144236.GB13248@quack2.suse.cz> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9643 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 mlxlogscore=999 bulkscore=0 suspectscore=0 mlxscore=0 adultscore=0 malwarescore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006050134 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9643 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 adultscore=0 suspectscore=0 cotscore=-2147483648 bulkscore=0 clxscore=1015 impostorscore=0 priorityscore=1501 malwarescore=0 mlxlogscore=999 spamscore=0 lowpriorityscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006050134 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, Jun 05, 2020 at 04:42:36PM +0200, Jan Kara wrote: > On Fri 05-06-20 12:43:54, Dan Carpenter wrote: > > I wonder if maybe the best fix is to re-add the "if (!res) " check back > > to blkdev_get(). > > Well, it won't be that simple since we need to call bd_abort_claiming() > under bdev->bd_mutex. And the fact that __blkdev_get() frees the reference > you pass to it is somewhat subtle and surprising so I think we are better > off getting rid of that. Fair enough. Jason Yan sent a v3 of this patch that frees "whole". I've looked it over pretty close and I think it's probably correct. (not that my opinion should count for much because I don't know this code very well at all). regards, dan carpenter