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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_SANE_1 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 E91DEC433FF for ; Mon, 5 Aug 2019 03:08:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C77F12075C for ; Mon, 5 Aug 2019 03:08:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727049AbfHEDI0 (ORCPT ); Sun, 4 Aug 2019 23:08:26 -0400 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]:37663 "EHLO out30-130.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726765AbfHEDI0 (ORCPT ); Sun, 4 Aug 2019 23:08:26 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04395;MF=chge@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0TYeMQGU_1564974500; Received: from IT-C02YD3Q7JG5H.local(mailfrom:chge@linux.alibaba.com fp:SMTPD_---0TYeMQGU_1564974500) by smtp.aliyun-inc.com(127.0.0.1); Mon, 05 Aug 2019 11:08:21 +0800 Subject: Re: [Ocfs2-devel] [PATCH 1/3 v2] fs: ocfs2: Fix possible null-pointer dereferences in ocfs2_xa_prepare_entry() To: Joseph Qi , Jia-Ju Bai , mark@fasheh.com, jlbec@evilplan.org, Andrew Morton Cc: linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com, Andrew Morton References: <20190726101447.9153-1-baijiaju1990@gmail.com> From: Changwei Ge Message-ID: <2b0fa21a-3351-0e3c-4355-54f22559a772@linux.alibaba.com> Date: Mon, 5 Aug 2019 11:08:20 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jia-Ju, Please checkout my comments inline. On 2019/7/27 8:49 上午, Joseph Qi wrote: > > On 19/7/26 18:14, Jia-Ju Bai wrote: >> In ocfs2_xa_prepare_entry(), there is an if statement on line 2136 to >> check whether loc->xl_entry is NULL: >> if (loc->xl_entry) >> >> When loc->xl_entry is NULL, it is used on line 2158: >> ocfs2_xa_add_entry(loc, name_hash); This won't deference a NULL ->xl_entry because ->xlo_add_entry() is already called to whether ocfs2_xa_block_add_entry() or ocfs2_xa_bucket_add_entry() From the function name we can tell the intention it wants to add entry so of course it should be NULL before calling it. Thanks, Changwei >> loc->xl_entry->xe_name_hash = cpu_to_le32(name_hash); >> loc->xl_entry->xe_name_offset = cpu_to_le16(loc->xl_size); >> and line 2164: >> ocfs2_xa_add_namevalue(loc, xi); >> loc->xl_entry->xe_value_size = cpu_to_le64(xi->xi_value_len); >> loc->xl_entry->xe_name_len = xi->xi_name_len; >> >> Thus, possible null-pointer dereferences may occur. >> >> To fix these bugs, if loc-xl_entry is NULL, ocfs2_xa_prepare_entry() >> abnormally returns with -EINVAL. >> >> These bugs are found by a static analysis tool STCheck written by us. >> >> Signed-off-by: Jia-Ju Bai > Reviewed-by: Joseph Qi >> --- >> v2: >> * Directly return -EINVAL if loc-xl_entry is NULL. >> Thank Joseph for helpful advice. >> >> --- >> fs/ocfs2/xattr.c | 44 +++++++++++++++++++++++--------------------- >> 1 file changed, 23 insertions(+), 21 deletions(-) >> >> diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c >> index 385f3aaa2448..4b876c82a35c 100644 >> --- a/fs/ocfs2/xattr.c >> +++ b/fs/ocfs2/xattr.c >> @@ -2133,29 +2133,31 @@ static int ocfs2_xa_prepare_entry(struct ocfs2_xa_loc *loc, >> if (rc) >> goto out; >> >> - if (loc->xl_entry) { >> - if (ocfs2_xa_can_reuse_entry(loc, xi)) { >> - orig_value_size = loc->xl_entry->xe_value_size; >> - rc = ocfs2_xa_reuse_entry(loc, xi, ctxt); >> - if (rc) >> - goto out; >> - goto alloc_value; >> - } >> + if (!loc->xl_entry) { >> + rc = -EINVAL; >> + goto out; >> + } >> >> - if (!ocfs2_xattr_is_local(loc->xl_entry)) { >> - orig_clusters = ocfs2_xa_value_clusters(loc); >> - rc = ocfs2_xa_value_truncate(loc, 0, ctxt); >> - if (rc) { >> - mlog_errno(rc); >> - ocfs2_xa_cleanup_value_truncate(loc, >> - "overwriting", >> - orig_clusters); >> - goto out; >> - } >> + if (ocfs2_xa_can_reuse_entry(loc, xi)) { >> + orig_value_size = loc->xl_entry->xe_value_size; >> + rc = ocfs2_xa_reuse_entry(loc, xi, ctxt); >> + if (rc) >> + goto out; >> + goto alloc_value; >> + } >> + >> + if (!ocfs2_xattr_is_local(loc->xl_entry)) { >> + orig_clusters = ocfs2_xa_value_clusters(loc); >> + rc = ocfs2_xa_value_truncate(loc, 0, ctxt); >> + if (rc) { >> + mlog_errno(rc); >> + ocfs2_xa_cleanup_value_truncate(loc, >> + "overwriting", >> + orig_clusters); >> + goto out; >> } >> - ocfs2_xa_wipe_namevalue(loc); >> - } else >> - ocfs2_xa_add_entry(loc, name_hash); >> + } >> + ocfs2_xa_wipe_namevalue(loc); >> >> /* >> * If we get here, we have a blank entry. Fill it. We grow our >> > _______________________________________________ > Ocfs2-devel mailing list > Ocfs2-devel@oss.oracle.com > https://oss.oracle.com/mailman/listinfo/ocfs2-devel