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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, FREEMAIL_REPLYTO_END_DIGIT,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,USER_AGENT_MUTT 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 90878C43610 for ; Mon, 26 Nov 2018 10:36:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 419CC2089F for ; Mon, 26 Nov 2018 10:36:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="S3VmWlKc" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 419CC2089F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=163.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726237AbeKZVaP (ORCPT ); Mon, 26 Nov 2018 16:30:15 -0500 Received: from m12-17.163.com ([220.181.12.17]:43797 "EHLO m12-17.163.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726176AbeKZVaO (ORCPT ); Mon, 26 Nov 2018 16:30:14 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=Date:From:Subject:Message-ID:MIME-Version; bh=/lgGf ku1gWV1fcLw4wfxQkxc6DWHs5mkrsP+geSG0gU=; b=S3VmWlKco/m+z2ZOAc3uN HjTfSm/+FJRaGqZOMGv2adUlOA9MdCrJRAwWdjzIJaowyy+GE7o2q+1U0CruzcLO k9ntSOvSSCyzIo0T/jF0t4ra8O/ct0ZM42eKQATsq1kAq7bPGjbx6w50oqqeteL8 AraC4DjeMKkluhBJLjb3gI= Received: from bp (unknown [106.120.213.96]) by smtp13 (Coremail) with SMTP id EcCowABnbo6izPtb_mTHBg--.38780S2; Mon, 26 Nov 2018 18:36:18 +0800 (CST) Date: Mon, 26 Nov 2018 18:36:19 +0800 From: PanBian To: Carlos Maiolino Cc: "Darrick J. Wong" , linux-xfs@vger.kernel.org, Brian Foster , Dave Chinner , linux-kernel@vger.kernel.org Subject: Re: [PATCH] xfs: libxfs: move xfs_perag_put late Message-ID: <20181126103619.GA95394@bp> Reply-To: PanBian References: <1543052660-58625-1-git-send-email-bianpan2016@163.com> <20181126093139.cgojlmtubzuzdb23@hades.usersys.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181126093139.cgojlmtubzuzdb23@hades.usersys.redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-CM-TRANSID: EcCowABnbo6izPtb_mTHBg--.38780S2 X-Coremail-Antispam: 1Uf129KBjvdXoWrZr1xXF45KrWkZry5Cw1kAFb_yoW3KrXEgr W2qrZ7Cw4vgr4SgF47Wr43XF45KF4UGw48Wr93XFWS934UJw4rC397Grn5Zwn5XrZrtr45 uws8WaykJa429jkaLaAFLSUrUUUUUb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUvcSsGvfC2KfnxnUUI43ZEXa7IUnWlk3UUUUU== X-Originating-IP: [106.120.213.96] X-CM-SenderInfo: held01tdqsiiqw6rljoofrz/xtbBUQMLclaD0UQEogAAsN Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 26, 2018 at 10:31:39AM +0100, Carlos Maiolino wrote: > On Sat, Nov 24, 2018 at 05:44:20PM +0800, Pan Bian wrote: > > The function xfs_alloc_get_freelist calls xfs_perag_put to drop the > > reference. In this case, pag may be released. However, > > pag->pagf_btreeblks is read and write after the put operation. This may > > result in a use-after-free bug. This patch moves the put operation late. > > > > The patch looks reasonable, can you detail more how did you find it? Via code > inspection of you hit this user-after-free in some way? I wrote a tool to check such bugs statically. It first scans the source code to extract paired alloc/free functions. Equipped with such functions, it performs an intra-procedural data flow analysis to detect mismatched alloc/free bugs and use-after-free bugs. Best regards, Pan Bian