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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,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 0C4C0C4361B for ; Tue, 15 Dec 2020 08:40:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BB2B52231F for ; Tue, 15 Dec 2020 08:40:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727309AbgLOIkO (ORCPT ); Tue, 15 Dec 2020 03:40:14 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:9608 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727135AbgLOIkC (ORCPT ); Tue, 15 Dec 2020 03:40:02 -0500 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4CwBVY2fqmzM5T4; Tue, 15 Dec 2020 16:38:29 +0800 (CST) Received: from [10.174.179.9] (10.174.179.9) by smtp.huawei.com (10.3.19.204) with Microsoft SMTP Server (TLS) id 14.3.498.0; Tue, 15 Dec 2020 16:39:08 +0800 Subject: Re: [PATCH] cgroup: Fix memory leak when parsing multiple source parameters To: Qinglang Miao , Tejun Heo , Johannes Weiner CC: , References: <20201209121322.77665-1-miaoqinglang@huawei.com> From: Zefan Li Message-ID: Date: Tue, 15 Dec 2020 16:39:00 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20201209121322.77665-1-miaoqinglang@huawei.com> Content-Type: text/plain; charset="gbk" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.179.9] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/12/9 20:13, Qinglang Miao wrote: > A memory leak is found in cgroup1_parse_param() when multiple source > parameters overwrite fc->source in the fs_context struct without free. > > unreferenced object 0xffff888100d930e0 (size 16): > comm "mount", pid 520, jiffies 4303326831 (age 152.783s) > hex dump (first 16 bytes): > 74 65 73 74 6c 65 61 6b 00 00 00 00 00 00 00 00 testleak........ > backtrace: > [<000000003e5023ec>] kmemdup_nul+0x2d/0xa0 > [<00000000377dbdaa>] vfs_parse_fs_string+0xc0/0x150 > [<00000000cb2b4882>] generic_parse_monolithic+0x15a/0x1d0 > [<000000000f750198>] path_mount+0xee1/0x1820 > [<0000000004756de2>] do_mount+0xea/0x100 > [<0000000094cafb0a>] __x64_sys_mount+0x14b/0x1f0 > > Fix this bug by permitting a single source parameter and rejecting with > an error all subsequent ones. > > Fixes: 8d2451f4994f ("cgroup1: switch to option-by-option parsing") > Reported-by: Hulk Robot > Signed-off-by: Qinglang Miao > --- > kernel/cgroup/cgroup-v1.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c > index 191c329e4..1fd7d3d18 100644 > --- a/kernel/cgroup/cgroup-v1.c > +++ b/kernel/cgroup/cgroup-v1.c > @@ -908,6 +908,9 @@ int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param) > opt = fs_parse(fc, cgroup1_fs_parameters, param, &result); > if (opt == -ENOPARAM) { > if (strcmp(param->key, "source") == 0) { > + if (fc->source) > + return invalf(fc, "Multiple sources not > + supported"); "never break user-visible strings such as printk messages because that breaks the ability to grep for them.", quoted from CodingStyle. Please fix this and you can add Reviewed-by: Zefan Li