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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 6476CC04E84 for ; Wed, 15 May 2019 08:23:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 41BBA20881 for ; Wed, 15 May 2019 08:23:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726690AbfEOIXr (ORCPT ); Wed, 15 May 2019 04:23:47 -0400 Received: from mx2.suse.de ([195.135.220.15]:33190 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726586AbfEOIXe (ORCPT ); Wed, 15 May 2019 04:23:34 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 1ACCFAF74; Wed, 15 May 2019 08:23:33 +0000 (UTC) Date: Wed, 15 May 2019 10:22:59 +0200 From: Oscar Salvador To: Konstantin Khlebnikov Cc: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org, Michal Hocko , Yang Shi , mkoutny@suse.com Subject: Re: [PATCH] mm: fix protection of mm_struct fields in get_cmdline() Message-ID: <20190515082222.GA21259@linux> References: <155790813764.2995.13706842444028749629.stgit@buzz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <155790813764.2995.13706842444028749629.stgit@buzz> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 15, 2019 at 11:15:37AM +0300, 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 This was already addressed by [1]? [1] https://patchwork.kernel.org/patch/10923003/ > --- > 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; > > -- Oscar Salvador SUSE L3