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=-4.6 required=3.0 tests=DATE_IN_PAST_12_24, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, USER_AGENT_MUTT 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 8BF3EC04AB1 for ; Sat, 11 May 2019 17:19:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 60724216C4 for ; Sat, 11 May 2019 17:19:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727589AbfEKRTo (ORCPT ); Sat, 11 May 2019 13:19:44 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:47199 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726968AbfEKRTo (ORCPT ); Sat, 11 May 2019 13:19:44 -0400 Received: from callcc.thunk.org (rrcs-67-53-55-100.west.biz.rr.com [67.53.55.100]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id x4BHJaQN030274 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sat, 11 May 2019 13:19:38 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id 7A41242002B; Fri, 10 May 2019 22:01:59 -0400 (EDT) Date: Fri, 10 May 2019 22:01:59 -0400 From: "Theodore Ts'o" To: Sahitya Tummala Cc: Andreas Dilger , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] ext4: fix use-after-free in dx_release() Message-ID: <20190511020159.GF2534@mit.edu> Mail-Followup-To: Theodore Ts'o , Sahitya Tummala , Andreas Dilger , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org References: <1557304443-18653-1-git-send-email-stummala@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1557304443-18653-1-git-send-email-stummala@codeaurora.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Wed, May 08, 2019 at 02:04:03PM +0530, Sahitya Tummala wrote: > The buffer_head (frames[0].bh) and it's corresping page can be > potentially free'd once brelse() is done inside the for loop > but before the for loop exits in dx_release(). It can be free'd > in another context, when the page cache is flushed via > drop_caches_sysctl_handler(). This results into below data abort > when accessing info->indirect_levels in dx_release(). > > Unable to handle kernel paging request at virtual address ffffffc17ac3e01e > Call trace: > dx_release+0x70/0x90 > ext4_htree_fill_tree+0x2d4/0x300 > ext4_readdir+0x244/0x6f8 > iterate_dir+0xbc/0x160 > SyS_getdents64+0x94/0x174 > > Signed-off-by: Sahitya Tummala Nice catch. Thanks, applied. - Ted