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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 BCBF2C2D0C2 for ; Mon, 30 Dec 2019 17:06:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8CD3420718 for ; Mon, 30 Dec 2019 17:06:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727162AbfL3RGk (ORCPT ); Mon, 30 Dec 2019 12:06:40 -0500 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:60404 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726675AbfL3RGj (ORCPT ); Mon, 30 Dec 2019 12:06:39 -0500 Received: from callcc.thunk.org ([173.239.199.158]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id xBUH6Tfw022174 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 30 Dec 2019 12:06:31 -0500 Received: by callcc.thunk.org (Postfix, from userid 15806) id 8F515420485; Mon, 30 Dec 2019 12:06:28 -0500 (EST) Date: Mon, 30 Dec 2019 12:06:28 -0500 From: "Theodore Y. Ts'o" To: Wang Shilong Cc: linux-ext4@vger.kernel.org, adilger@dilger.ca, lixi@ddn.com, wshilong@ddn.com Subject: Re: [PATCH 2/2] e2fsck: fix use after free in calculate_tree() Message-ID: <20191230170628.GB125106@mit.edu> References: <1574759039-7429-1-git-send-email-wangshilong1991@gmail.com> <1574759039-7429-2-git-send-email-wangshilong1991@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1574759039-7429-2-git-send-email-wangshilong1991@gmail.com> Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Tue, Nov 26, 2019 at 06:03:59PM +0900, Wang Shilong wrote: > @@ -725,12 +728,18 @@ static errcode_t calculate_tree(ext2_filsys fs, > return retval; > } > if (c3 == 0) { > + int delta1 = int_offset;; > + int delta2 = (char *)root - outdir->buf; > + > retval = alloc_blocks(fs, &limit, &int_ent, > &dx_ent, &int_offset, > NULL, outdir, i, &c2, > &c3); > if (retval) > return retval; > + /* outdir->buf might be reallocated */ > + int_limit = (struct ext2_dx_countlimit *)(outdir->buf + delta1); > + root = (struct ext2_dx_entry *)(outdir->buf + delta2); > > } > dx_ent->block = ext2fs_cpu_to_le32(i); Um, are you sure int delta1 = int_offset;; is correct? I would think int delta1 = (char *)int_limit - outdir->buf; is what is needed; it's certainly much more clear. - Ted