From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ua0-f199.google.com (mail-ua0-f199.google.com [209.85.217.199]) by kanga.kvack.org (Postfix) with ESMTP id E3DDE6B0005 for ; Tue, 13 Feb 2018 16:43:51 -0500 (EST) Received: by mail-ua0-f199.google.com with SMTP id s7so5041121uaj.21 for ; Tue, 13 Feb 2018 13:43:51 -0800 (PST) Received: from mail-sor-f41.google.com (mail-sor-f41.google.com. [209.85.220.41]) by mx.google.com with SMTPS id r11sor4713745vkf.212.2018.02.13.13.43.50 for (Google Transport Security); Tue, 13 Feb 2018 13:43:50 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <20180124175631.22925-1-igor.stoppa@huawei.com> <20180124175631.22925-5-igor.stoppa@huawei.com> <20180126053542.GA30189@bombadil.infradead.org> <8818bfd4-dd9f-f279-0432-69b59531bd41@huawei.com> <17e5b515-84c8-dca2-1695-cdf819834ea2@huawei.com> <414027d3-dd73-cf11-dc2a-e8c124591646@redhat.com> From: Kees Cook Date: Tue, 13 Feb 2018 13:43:49 -0800 Message-ID: Subject: Re: [kernel-hardening] [PATCH 4/6] Protectable Memory Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Laura Abbott Cc: Jann Horn , Igor Stoppa , Boris Lukashev , Christopher Lameter , Matthew Wilcox , Jerome Glisse , Michal Hocko , Christoph Hellwig , linux-security-module , Linux-MM , kernel list , Kernel Hardening On Tue, Feb 13, 2018 at 8:09 AM, Laura Abbott wrote: > No, arm64 doesn't fixup the aliases, mostly because arm64 uses larger > page sizes which can't be broken down at runtime. CONFIG_PAGE_POISONING > does use 4K pages which could be adjusted at runtime. So yes, you are > right we would have physmap exposure on arm64 as well. Errr, so that means even modules and kernel code are writable via the arm64 physmap? That seems extraordinarily bad. :( -Kees -- Kees Cook Pixel Security -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org