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=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 C540DC04E87 for ; Wed, 15 May 2019 08:15:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 978F420862 for ; Wed, 15 May 2019 08:15:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="yiIhTfm8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726546AbfEOIPm (ORCPT ); Wed, 15 May 2019 04:15:42 -0400 Received: from forwardcorp1p.mail.yandex.net ([77.88.29.217]:37772 "EHLO forwardcorp1p.mail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725876AbfEOIPm (ORCPT ); Wed, 15 May 2019 04:15:42 -0400 Received: from mxbackcorp2j.mail.yandex.net (mxbackcorp2j.mail.yandex.net [IPv6:2a02:6b8:0:1619::119]) by forwardcorp1p.mail.yandex.net (Yandex) with ESMTP id A73FB2E0987; Wed, 15 May 2019 11:15:38 +0300 (MSK) Received: from smtpcorp1o.mail.yandex.net (smtpcorp1o.mail.yandex.net [2a02:6b8:0:1a2d::30]) by mxbackcorp2j.mail.yandex.net (nwsmtp/Yandex) with ESMTP id RoCJEKO4OP-Fc0KCJcQ; Wed, 15 May 2019 11:15:38 +0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1557908138; bh=jHxTX7+w5XRXWiyeoOBtShSglDK2yw1HqwPBfT2YxAA=; h=Message-ID:Date:To:From:Subject:Cc; b=yiIhTfm8Y8WhZ27MzSCHygSHiu5oBt8MnnCw4imtDEH6qA2novSoggL0Mk1CNqZ9T 7xF4+sJ+Uco+w51uWRsqF5JueXBt2YYU1CZvrsjb3//DVbmxezl4Kkc7S2+eC/xLEJ XdmVbHG1DwYMOOkK8yT+YETJRQD++p45vkpsltKw= Authentication-Results: mxbackcorp2j.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-red.dhcp.yndx.net (dynamic-red.dhcp.yndx.net [2a02:6b8:0:40c:ed19:3833:7ce1:2324]) by smtpcorp1o.mail.yandex.net (nwsmtp/Yandex) with ESMTPSA id TMPGL1lslS-Fbl0Xd6Q; Wed, 15 May 2019 11:15:37 +0300 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client certificate not present) Subject: [PATCH] mm: fix protection of mm_struct fields in get_cmdline() From: Konstantin Khlebnikov To: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org Cc: Michal Hocko , Yang Shi Date: Wed, 15 May 2019 11:15:37 +0300 Message-ID: <155790813764.2995.13706842444028749629.stgit@buzz> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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;