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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 AFE8BC433E2 for ; Thu, 17 Sep 2020 09:41:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 678092083B for ; Thu, 17 Sep 2020 09:41:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="IaeDatMS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726477AbgIQJlE (ORCPT ); Thu, 17 Sep 2020 05:41:04 -0400 Received: from mail.skyhub.de ([5.9.137.197]:54578 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726236AbgIQJlE (ORCPT ); Thu, 17 Sep 2020 05:41:04 -0400 Received: from zn.tnic (p200300ec2f1053000730ae91ea344e59.dip0.t-ipconnect.de [IPv6:2003:ec:2f10:5300:730:ae91:ea34:4e59]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 29B441EC032C; Thu, 17 Sep 2020 11:41:02 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1600335662; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=gSRn4R+wsZrRg7X+q05/zOo+dEqKEeyKAGD5yN2Wvyw=; b=IaeDatMSe+U4UkaBNx4hd+Tv+6elqn59PZgTfmavwQQ28/3FCxcHa685ADgPUvjpKT5oPn +hZUJBAnG/MUfZw5PQSuqVPVEVwP9eamUQ82b/PB5tyK1+Sl50R7DEfdTE0c8raLBodD73 lR3q5YYMnm33Oi1/gnLhO0JWfWWIoqY= Date: Thu, 17 Sep 2020 11:40:55 +0200 From: Borislav Petkov To: Arvind Sankar Cc: x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86/cmdline: Disable instrumentation of cmdline unconditionally Message-ID: <20200917094055.GF31960@zn.tnic> References: <20200906154637.1618112-1-nivedita@alum.mit.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200906154637.1618112-1-nivedita@alum.mit.edu> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Sep 06, 2020 at 11:46:37AM -0400, Arvind Sankar wrote: > On 32-bit, cmdline_find_option_bool() is used before paging is enabled, > from check_loader_disabled_bsp() in the early microcode loader. > Instrumentation options that insert accesses to global data will likely > crash or corrupt memory at this point. What is the use case here, can you trigger an actual crash? -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette