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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 7F03EC04E53 for ; Wed, 15 May 2019 08:38:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5DF132082E for ; Wed, 15 May 2019 08:38:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726472AbfEOIi3 (ORCPT ); Wed, 15 May 2019 04:38:29 -0400 Received: from relay.sw.ru ([185.231.240.75]:48082 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725876AbfEOIi2 (ORCPT ); Wed, 15 May 2019 04:38:28 -0400 Received: from [172.16.25.169] by relay.sw.ru with esmtp (Exim 4.91) (envelope-from ) id 1hQpQZ-0006hD-8M; Wed, 15 May 2019 11:38:19 +0300 Subject: Re: [PATCH] mm: fix protection of mm_struct fields in get_cmdline() To: Konstantin Khlebnikov , linux-mm@kvack.org, mkoutny@suse.com, Andrew Morton , linux-kernel@vger.kernel.org Cc: Michal Hocko , Yang Shi References: <155790813764.2995.13706842444028749629.stgit@buzz> From: Kirill Tkhai Message-ID: Date: Wed, 15 May 2019 11:38:18 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <155790813764.2995.13706842444028749629.stgit@buzz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Konstantin, On 15.05.2019 11:15, Konstantin Khlebnikov wrote: > Since commit 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start| > end and env_start|end in mm_struct") related mm fields are protected with > separate spinlock and mmap_sem held for read is not enough for protection. > > Fixes: 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct") > Signed-off-by: Konstantin Khlebnikov is this already fixed in Michal's series: https://lkml.org/lkml/2019/5/2/422 ? Thanks, Kirill > --- > mm/util.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/util.c b/mm/util.c > index e2e4f8c3fa12..540e7c157cf2 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -717,12 +717,12 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen) > if (!mm->arg_end) > goto out_mm; /* Shh! No looking before we're done */ > > - down_read(&mm->mmap_sem); > + spin_lock(&mm->arg_lock); > arg_start = mm->arg_start; > arg_end = mm->arg_end; > env_start = mm->env_start; > env_end = mm->env_end; > - up_read(&mm->mmap_sem); > + spin_unlock(&mm->arg_lock); > > len = arg_end - arg_start; > >