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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A093C433F5 for ; Thu, 30 Sep 2021 01:55:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 77B9461872 for ; Thu, 30 Sep 2021 01:55:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347650AbhI3B4b (ORCPT ); Wed, 29 Sep 2021 21:56:31 -0400 Received: from out30-57.freemail.mail.aliyun.com ([115.124.30.57]:54944 "EHLO out30-57.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233941AbhI3B43 (ORCPT ); Wed, 29 Sep 2021 21:56:29 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R261e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04395;MF=joseph.qi@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0Uq41Vho_1632966885; Received: from B-D1K7ML85-0059.local(mailfrom:joseph.qi@linux.alibaba.com fp:SMTPD_---0Uq41Vho_1632966885) by smtp.aliyun-inc.com(127.0.0.1); Thu, 30 Sep 2021 09:54:46 +0800 Subject: Re: [PATCH v2] ocfs2: mount fails with buffer overflow in strlen To: Valentin Vidic , akpm Cc: Mark Fasheh , Joel Becker , ocfs2-devel@oss.oracle.com, linux-kernel@vger.kernel.org References: <1ab61ba3-8c9b-092c-7843-9c45b58e3987@linux.alibaba.com> <20210929180654.32460-1-vvidic@valentin-vidic.from.hr> From: Joseph Qi Message-ID: Date: Thu, 30 Sep 2021 09:54:45 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20210929180654.32460-1-vvidic@valentin-vidic.from.hr> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/30/21 2:06 AM, Valentin Vidic wrote: > Starting with kernel 5.11 built with CONFIG_FORTIFY_SOURCE mouting an > ocfs2 filesystem with either o2cb or pcmk cluster stack fails with the > trace below. Problem seems to be that strings for cluster stack and > cluster name are not guaranteed to be null terminated in the disk > representation, while strlcpy assumes that the source string is always > null terminated. This causes a read outside of the source string > triggering the buffer overflow detection. > > detected buffer overflow in strlen > ------------[ cut here ]------------ > kernel BUG at lib/string.c:1149! > invalid opcode: 0000 [#1] SMP PTI > CPU: 1 PID: 910 Comm: mount.ocfs2 Not tainted 5.14.0-1-amd64 #1 > Debian 5.14.6-2 > RIP: 0010:fortify_panic+0xf/0x11 > ... > Call Trace: > ocfs2_initialize_super.isra.0.cold+0xc/0x18 [ocfs2] > ocfs2_fill_super+0x359/0x19b0 [ocfs2] > mount_bdev+0x185/0x1b0 > ? ocfs2_remount+0x440/0x440 [ocfs2] > legacy_get_tree+0x27/0x40 > vfs_get_tree+0x25/0xb0 > path_mount+0x454/0xa20 > __x64_sys_mount+0x103/0x140 > do_syscall_64+0x3b/0xc0 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > Signed-off-by: Valentin Vidic Reviewed-by: Joseph Qi > --- > v2: update description, add comment, drop null termination > > fs/ocfs2/super.c | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-) > > diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c > index c86bd4e60e20..5c914ce9b3ac 100644 > --- a/fs/ocfs2/super.c > +++ b/fs/ocfs2/super.c > @@ -2167,11 +2167,17 @@ static int ocfs2_initialize_super(struct super_block *sb, > } > > if (ocfs2_clusterinfo_valid(osb)) { > + /* > + * ci_stack and ci_cluster in ocfs2_cluster_info may not be null > + * terminated, so make sure no overflow happens here by using > + * memcpy. Destination strings will always be null terminated > + * because osb is allocated using kzalloc. > + */ > osb->osb_stackflags = > OCFS2_RAW_SB(di)->s_cluster_info.ci_stackflags; > - strlcpy(osb->osb_cluster_stack, > + memcpy(osb->osb_cluster_stack, > OCFS2_RAW_SB(di)->s_cluster_info.ci_stack, > - OCFS2_STACK_LABEL_LEN + 1); > + OCFS2_STACK_LABEL_LEN); > if (strlen(osb->osb_cluster_stack) != OCFS2_STACK_LABEL_LEN) { > mlog(ML_ERROR, > "couldn't mount because of an invalid " > @@ -2180,9 +2186,9 @@ static int ocfs2_initialize_super(struct super_block *sb, > status = -EINVAL; > goto bail; > } > - strlcpy(osb->osb_cluster_name, > + memcpy(osb->osb_cluster_name, > OCFS2_RAW_SB(di)->s_cluster_info.ci_cluster, > - OCFS2_CLUSTER_NAME_LEN + 1); > + OCFS2_CLUSTER_NAME_LEN); > } else { > /* The empty string is identical with classic tools that > * don't know about s_cluster_info. */ >