From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754852AbbI1VQS (ORCPT <rfc822;w@1wt.eu>);
	Mon, 28 Sep 2015 17:16:18 -0400
Received: from terminus.zytor.com ([198.137.202.10]:58059 "EHLO mail.zytor.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1754440AbbI1VQQ (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Mon, 28 Sep 2015 17:16:16 -0400
Subject: Re: rwx mapping between ex_table and rodata
To: Ingo Molnar <mingo@kernel.org>, Kees Cook <keescook@chromium.org>
References: <56045BC4.7000604@tycho.nsa.gov> <56045C8A.50102@tycho.nsa.gov>
 <CAGXu5j+tTR=x9RTOFvqQP7+W7DFR6N+GUP__uvAicrfTBU1B7w@mail.gmail.com>
 <20150925072259.GA17639@gmail.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>, "x86@kernel.org" <x86@kernel.org>,
        lkml <linux-kernel@vger.kernel.org>
From: "H. Peter Anvin" <hpa@zytor.com>
Message-ID: <5609AE16.2070204@zytor.com>
Date: Mon, 28 Sep 2015 14:16:06 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101
 Thunderbird/38.2.0
MIME-Version: 1.0
In-Reply-To: <20150925072259.GA17639@gmail.com>
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 09/25/2015 12:22 AM, Ingo Molnar wrote:
>>
>> To me it looks like another alignment/padding issue like got fixed
>> before. The space between __ex_table and rodata is (seems?) unused, so
>> the default page table permissions end up being W+X. Can we fix the
>> default to be NX instead? It'll make these bugs stay gone.
> 
> Yeah. Wanna send a patch for that?
> 

At least in the high mapping space, the default should be no permissions
(not present), rather than just NX.

	-hpa