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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 4C278C433DF for ; Tue, 26 May 2020 16:32:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 22961207FB for ; Tue, 26 May 2020 16:32:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590510760; bh=aH1fxzKkh8oPDxVH7mWTxxRoboBCqxnYW/72VwKzH5s=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=UHmww19y0dlm2w9YX7FNE2oq7wy0DofG3gbmrCV4epd9IP96kd5WU3uVFem0S+/2w SmuwIZK65epaFw3MyB3Nik1+8TgKSG+pljFKEBz5IiAKHNESn8nFKDd1LzNEIlSWcF JEQ+spipHuauKQYjI1I8wXJZKNHZ0DeCSHfvgqIQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388828AbgEZQcj (ORCPT ); Tue, 26 May 2020 12:32:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:54644 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388061AbgEZQcj (ORCPT ); Tue, 26 May 2020 12:32:39 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 916502073B; Tue, 26 May 2020 16:32:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590510759; bh=aH1fxzKkh8oPDxVH7mWTxxRoboBCqxnYW/72VwKzH5s=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=C8HUlHTjOdQmagDAuTUKqO201Qq3KYFEEwj2yfxa6nAttPsk8i8j6Y3EIyqsHG6Xf uaoW31+bxcYnB7IUywcCG+uOyvURvdgqXbaB+EPJfnZzo1yMRWa3vjAj1zUw5KM7OR D1IUnpfdN6H5zVXeFabr5gbl9cS53KDljOIVzRyE= Date: Tue, 26 May 2020 18:32:35 +0200 From: Greg KH To: Andi Kleen Cc: Andi Kleen , x86@kernel.org, keescook@chromium.org, linux-kernel@vger.kernel.org, sashal@kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v1] x86: Pin cr4 FSGSBASE Message-ID: <20200526163235.GA42137@kroah.com> References: <20200526052848.605423-1-andi@firstfloor.org> <20200526065618.GC2580410@kroah.com> <20200526154835.GW499505@tassilo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200526154835.GW499505@tassilo.jf.intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 26, 2020 at 08:48:35AM -0700, Andi Kleen wrote: > On Tue, May 26, 2020 at 08:56:18AM +0200, Greg KH wrote: > > On Mon, May 25, 2020 at 10:28:48PM -0700, Andi Kleen wrote: > > > From: Andi Kleen > > > > > > Since there seem to be kernel modules floating around that set > > > FSGSBASE incorrectly, prevent this in the CR4 pinning. Currently > > > CR4 pinning just checks that bits are set, this also checks > > > that the FSGSBASE bit is not set, and if it is clears it again. > > > > So we are trying to "protect" ourselves from broken out-of-tree kernel > > modules now? > > Well it's a specific case where we know they're opening a root hole > unintentionally. This is just an pragmatic attempt to protect the users in the > short term. Can't you just go and fix those out-of-tree kernel modules instead? What's keeping you all from just doing that instead of trying to force the kernel to play traffic cop? thanks, greg k-h