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 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 BBA44C10F27 for ; Wed, 11 Mar 2020 13:13:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9363C22527 for ; Wed, 11 Mar 2020 13:13:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583932395; bh=1oMyqZhhouDDxXXOvmwgcXgxgUJvVopRYYmca3y7TKk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=f5ZcKouOYoYkcx91Kxp92pjEgXiZHRPnwa48bk/zH+GoWjxYrHi9ZQKZfBXLBJl87 /IRuvO71HMdFAcFIG5CDfOB3QDZNTl1rGVTJLljBrcGx3CfUHXdsZ72UTUtOsLSll+ RLCHr2mPsa/sit5yl1rFVwohJC5xmpznjlHmuyAU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729435AbgCKNNP (ORCPT ); Wed, 11 Mar 2020 09:13:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:45774 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729414AbgCKNNP (ORCPT ); Wed, 11 Mar 2020 09:13:15 -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 7E2E322464; Wed, 11 Mar 2020 13:13:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583932394; bh=1oMyqZhhouDDxXXOvmwgcXgxgUJvVopRYYmca3y7TKk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qxxNTPn7MlwKwTypoj3+toFl5CVBiuIbgmaxMRvo9wEkhDAEr9ZveGaTfHuY4+nZD htik0wu7e/K8QusJBFTZpVQD2ljJwL4xnxoY0DWyVQQHDVRK38Xqf4bguvDSo1OXcf frcmSmNL4rOhMQiW1Kvw2vDuscYgJCE/Znn75HRw= Date: Wed, 11 Mar 2020 14:13:11 +0100 From: Greg Kroah-Hartman To: Pavel Machek Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Ard Biesheuvel , Ingo Molnar , linux-efi@vger.kernel.org, Thomas Gleixner Subject: Re: [PATCH 4.19 84/86] efi/x86: Handle by-ref arguments covering multiple pages in mixed mode Message-ID: <20200311131311.GA3858095@kroah.com> References: <20200310124530.808338541@linuxfoundation.org> <20200310124535.409134291@linuxfoundation.org> <20200311130106.GB7285@duo.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200311130106.GB7285@duo.ucw.cz> Sender: linux-efi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org On Wed, Mar 11, 2020 at 02:01:07PM +0100, Pavel Machek wrote: > Hi! > > > Currently, the mixed mode runtime service wrappers require that all by-ref > > arguments that live in the vmalloc space have a size that is a power of 2, > > and are aligned to that same value. While this is a sensible way to > > construct an object that is guaranteed not to cross a page boundary, it is > > overly strict when it comes to checking whether a given object violates > > this requirement, as we can simply take the physical address of the first > > and the last byte, and verify that they point into the same physical > > page. > > Dunno. If start passing buffers that _sometime_ cross page boundaries, > we'll get hard to debug failures. Maybe original code is better > buecause it catches problems earlier? > > Furthermore, all existing code should pass aligned, 2^n size buffers, > so we should not need this in stable? For some crazy reason you cut out the reason I applied this patch to the stable tree. From the changelog text: Fixes: f6697df36bdf0bf7 ("x86/efi: Prevent mixed mode boot corruption with CONFIG_VMAP_STACK=y")