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=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 BCA85C433DB for ; Wed, 23 Dec 2020 23:08:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 78FB2223E4 for ; Wed, 23 Dec 2020 23:08:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727720AbgLWXIE convert rfc822-to-8bit (ORCPT ); Wed, 23 Dec 2020 18:08:04 -0500 Received: from lithops.sigma-star.at ([195.201.40.130]:53396 "EHLO lithops.sigma-star.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726746AbgLWXIE (ORCPT ); Wed, 23 Dec 2020 18:08:04 -0500 Received: from localhost (localhost [127.0.0.1]) by lithops.sigma-star.at (Postfix) with ESMTP id CAD8A627AFD1; Thu, 24 Dec 2020 00:07:21 +0100 (CET) Received: from lithops.sigma-star.at ([127.0.0.1]) by localhost (lithops.sigma-star.at [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id SGMQu-kVD2FX; Thu, 24 Dec 2020 00:07:21 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by lithops.sigma-star.at (Postfix) with ESMTP id 350BF6074003; Thu, 24 Dec 2020 00:07:21 +0100 (CET) Received: from lithops.sigma-star.at ([127.0.0.1]) by localhost (lithops.sigma-star.at [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id TI0iMxNtLuLf; Thu, 24 Dec 2020 00:07:21 +0100 (CET) Received: from lithops.sigma-star.at (lithops.sigma-star.at [195.201.40.130]) by lithops.sigma-star.at (Postfix) with ESMTP id 05DAD627AFD1; Thu, 24 Dec 2020 00:07:21 +0100 (CET) Date: Thu, 24 Dec 2020 00:07:20 +0100 (CET) From: Richard Weinberger To: Chengsong Ke Cc: Sascha Hauer , linux-mtd , linux-kernel , wangfangpeng1 , chengzhihao1 Message-ID: <244303467.160590.1608764840819.JavaMail.zimbra@nod.at> In-Reply-To: <20201223121536.6244-1-kechengsong@huawei.com> References: <20201223121536.6244-1-kechengsong@huawei.com> Subject: Re: [PATCH v2] ubifs: Fix read out-of-bounds in ubifs_jnl_write_inode() MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT X-Originating-IP: [195.201.40.130] X-Mailer: Zimbra 8.8.12_GA_3807 (ZimbraWebClient - FF78 (Linux)/8.8.12_GA_3809) Thread-Topic: ubifs: Fix read out-of-bounds in ubifs_jnl_write_inode() Thread-Index: 0xc6wfczRyckhgf1Nz6eomypQ1IBQg== Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Chengsong Ke, ----- Ursprüngliche Mail ----- > The memory area allocated in ubifs_jnl_write_inode() is not aligned with 8 > bytes: > ino_start = ino = kmalloc(write_len, GFP_NOFS); > > When ino_start passed into write_head -> ubifs_wbuf_write_nolock: > n = aligned_len >> c->max_write_shift; > if (n) { > n <<= c->max_write_shift; > err = ubifs_leb_write(c, wbuf->lnum, buf + written, wbuf->offs, n); > // Read oob occurs here, read n bytes from buf, and buf is passed from > @ino_start which is > // not 8 bytes aligned(write_len < n). Program read (n - write_len) more bytes. > } > > Reproducer: > 0. config KASAN && apply print.patch > 1. mount ubifs on /root/temp > 2. run test.sh What does test.sh do? > 3. cd /root/temp && ls // change atime for link_file > 4. wait 1~2 minutes > > In order to solve the read oob problem in ubifs_wbuf_write_nolock, just align > the write_len to > 8 bytes when alloc the memory. So that this patch will not affect the use of > write_len in other > functions, such as ubifs_jnl_write_inode->make_reservation and > ubifs_jnl_write_inode->ubifs_node_calc_hash. I gave this a second thought and I'm not so sure anymore what exactly is going on. The problem is real, I fully agree with you but I need to dig deeper into the journal and wbuf code to double check that we really fix the right thing and not just paper other something. Thanks, //richard