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=-12.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 4E14BC7112F for ; Mon, 21 Jan 2019 11:32:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2890F20663 for ; Mon, 21 Jan 2019 11:32:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728375AbfAULcy (ORCPT ); Mon, 21 Jan 2019 06:32:54 -0500 Received: from terminus.zytor.com ([198.137.202.136]:36785 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727159AbfAULcy (ORCPT ); Mon, 21 Jan 2019 06:32:54 -0500 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id x0LBWaor2496747 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Mon, 21 Jan 2019 03:32:36 -0800 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id x0LBWaNZ2496744; Mon, 21 Jan 2019 03:32:36 -0800 Date: Mon, 21 Jan 2019 03:32:36 -0800 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Kangjie Lu Message-ID: Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, torvalds@linux-foundation.org, tglx@linutronix.de, hpa@zytor.com, stable@vger.kernel.org, mingo@kernel.org, kjlu@umn.edu Reply-To: mingo@kernel.org, kjlu@umn.edu, tglx@linutronix.de, hpa@zytor.com, stable@vger.kernel.org, peterz@infradead.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org In-Reply-To: <20190109074524.10176-1-kjlu@umn.edu> References: <20190109074524.10176-1-kjlu@umn.edu> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched/core: Fix a potential double-fetch bug in sched_copy_attr() Git-Commit-ID: 120e4e76857ddbc9268e1aa3f9de61a498e84618 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 120e4e76857ddbc9268e1aa3f9de61a498e84618 Gitweb: https://git.kernel.org/tip/120e4e76857ddbc9268e1aa3f9de61a498e84618 Author: Kangjie Lu AuthorDate: Wed, 9 Jan 2019 01:45:24 -0600 Committer: Ingo Molnar CommitDate: Mon, 21 Jan 2019 11:26:17 +0100 sched/core: Fix a potential double-fetch bug in sched_copy_attr() "uattr->size" is copied in from user space and checked. However, it is copied in again after the security check. A malicious user may race to change it. The fix sets uattr->size to be the checked size. Signed-off-by: Kangjie Lu Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: pakki001@umn.edu Cc: Link: https://lkml.kernel.org/r/20190109074524.10176-1-kjlu@umn.edu Signed-off-by: Ingo Molnar --- kernel/sched/core.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index a674c7db2f29..d4d3514c4fe9 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4499,6 +4499,9 @@ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *a if (ret) return -EFAULT; + /* In case attr->size was changed by user-space: */ + attr->size = size; + /* * XXX: Do we want to be lenient like existing syscalls; or do we want * to be strict and return an error on out-of-bounds values?