Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754848Ab3JYNfJ (ORCPT ); Fri, 25 Oct 2013 09:35:09 -0400 Received: from smtp.outflux.net ([198.145.64.163]:52017 "EHLO smtp.outflux.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753910Ab3JYNfH (ORCPT ); Fri, 25 Oct 2013 09:35:07 -0400 Date: Fri, 25 Oct 2013 06:34:54 -0700 From: Kees Cook To: "H. Peter Anvin" Cc: "Yan, Zheng" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org Subject: RW and executable hole in page tables on x86_64 Message-ID: <20131025133454.GC4994@outflux.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Organization: Outflux X-HELO: www.outflux.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1372 Lines: 31 Hi, I've noticed there's a chunk of kernel memory still marked RW and x. See 0xffffffff82956000 below... ---[ High Kernel Mapping ]--- 0xffffffff80000000-0xffffffff81000000 16M pmd 0xffffffff81000000-0xffffffff81a00000 10M ro PSE GLB x pmd 0xffffffff81a00000-0xffffffff81e00000 4M ro PSE GLB NX pmd 0xffffffff81e00000-0xffffffff82200000 4M RW GLB NX pte 0xffffffff82200000-0xffffffff82800000 6M RW PSE GLB NX pmd 0xffffffff82800000-0xffffffff82956000 1368K RW GLB NX pte 0xffffffff82956000-0xffffffff82a00000 680K RW GLB x pte 0xffffffff82a00000-0xffffffffa0000000 470M pmd HPA looked at it for a bit, but it wasn't obvious what was going on. It's after the end of bss. I do note that the two adjacent regions add up to 2MiB. Is this some kind of leftover mapping? What is this region? Is there a sensible place to clean it up? Thanks, -Kees -- Kees Cook @outflux.net -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/