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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,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 62497C433EF for ; Tue, 21 Sep 2021 11:09:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3E5FF61175 for ; Tue, 21 Sep 2021 11:09:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232221AbhIULLA (ORCPT ); Tue, 21 Sep 2021 07:11:00 -0400 Received: from hosting.gsystem.sk ([212.5.213.30]:38256 "EHLO hosting.gsystem.sk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231956AbhIULK7 (ORCPT ); Tue, 21 Sep 2021 07:10:59 -0400 Received: from [192.168.1.3] (ns.gsystem.sk [62.176.172.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by hosting.gsystem.sk (Postfix) with ESMTPSA id 733C07A0222; Tue, 21 Sep 2021 13:09:29 +0200 (CEST) From: Ondrej Zary To: linux-kernel@vger.kernel.org Subject: Re: [tip: x86/core] x86/iopl: Fake iopl(3) CLI/STI usage Date: Tue, 21 Sep 2021 13:09:26 +0200 User-Agent: KMail/1.9.10 Cc: linux-tip-commits@vger.kernel.org, "Peter Zijlstra (Intel)" , Thomas Gleixner , x86@kernel.org References: <20210918090641.GD5106@worktop.programming.kicks-ass.net> <163220928593.25758.16098239507716851071.tip-bot2@tip-bot2> In-Reply-To: <163220928593.25758.16098239507716851071.tip-bot2@tip-bot2> X-KMail-QuotePrefix: > MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <202109211309.26518.linux@zary.sk> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 21 September 2021, tip-bot2 for Peter Zijlstra wrote: > The following commit has been merged into the x86/core branch of tip: > > Commit-ID: 32e1ae626f295152d1fc9a3375214133cbe62878 > Gitweb: https://git.kernel.org/tip/32e1ae626f295152d1fc9a3375214133cbe62878 > Author: Peter Zijlstra > AuthorDate: Fri, 17 Sep 2021 11:20:04 +02:00 > Committer: Peter Zijlstra > CommitterDate: Sat, 18 Sep 2021 12:18:32 +02:00 > > x86/iopl: Fake iopl(3) CLI/STI usage > > Since commit c8137ace5638 ("x86/iopl: Restrict iopl() permission > scope") it's possible to emulate iopl(3) using ioperm(), except for > the CLI/STI usage. > > Userspace CLI/STI usage is very dubious (read broken), since any > exception taken during that window can lead to rescheduling anyway (or > worse). The IOPL(2) manpage even states that usage of CLI/STI is highly > discouraged and might even crash the system. > > Of course, that won't stop people and HP has the dubious honour of > being the first vendor to be found using this in their hp-health > package. > > In order to enable this 'software' to still 'work', have the #GP treat > the CLI/STI instructions as NOPs when iopl(3). Warn the user that > their program is doing dubious things. > > Fixes: a24ca9976843 ("x86/iopl: Remove legacy IOPL option") > Reported-by: Ondrej Zary > Signed-off-by: Peter Zijlstra (Intel) > Reviewed-by: Thomas Gleixner > Link: https://lkml.kernel.org/r/20210918090641.GD5106@worktop.programming.kicks-ass.net Could this be backported to 5.10 kernel so it can get into the recently released Debian 11? -- Ondrej Zary