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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 9DA58C282DD for ; Thu, 18 Apr 2019 05:24:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6F79921479 for ; Thu, 18 Apr 2019 05:24:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731257AbfDRFYl (ORCPT ); Thu, 18 Apr 2019 01:24:41 -0400 Received: from relay1-d.mail.gandi.net ([217.70.183.193]:56715 "EHLO relay1-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725836AbfDRFYl (ORCPT ); Thu, 18 Apr 2019 01:24:41 -0400 X-Originating-IP: 79.86.19.127 Received: from [192.168.0.11] (127.19.86.79.rev.sfr.net [79.86.19.127]) (Authenticated sender: alex@ghiti.fr) by relay1-d.mail.gandi.net (Postfix) with ESMTPSA id 42730240002; Thu, 18 Apr 2019 05:24:33 +0000 (UTC) Subject: Re: [PATCH v3 03/11] arm64: Consider stack randomization for mmap base only when necessary To: Kees Cook Cc: Andrew Morton , Christoph Hellwig , Russell King , Catalin Marinas , Will Deacon , Ralf Baechle , Paul Burton , James Hogan , Palmer Dabbelt , Albert Ou , Alexander Viro , Luis Chamberlain , LKML , linux-arm-kernel , linux-mips@vger.kernel.org, linux-riscv@lists.infradead.org, "linux-fsdevel@vger.kernel.org" , Linux-MM References: <20190417052247.17809-1-alex@ghiti.fr> <20190417052247.17809-4-alex@ghiti.fr> From: Alex Ghiti Message-ID: Date: Thu, 18 Apr 2019 01:24:32 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: sv-FI Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/18/19 12:37 AM, Kees Cook wrote: > On Wed, Apr 17, 2019 at 12:26 AM Alexandre Ghiti wrote: >> Do not offset mmap base address because of stack randomization if >> current task does not want randomization. > Maybe mention that this makes this logic match the existing x86 behavior too? Ok I will add this in case of a v4. > >> Signed-off-by: Alexandre Ghiti > Acked-by: Kees Cook Thanks ! > > -Kees > >> --- >> arch/arm64/mm/mmap.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c >> index ed4f9915f2b8..ac89686c4af8 100644 >> --- a/arch/arm64/mm/mmap.c >> +++ b/arch/arm64/mm/mmap.c >> @@ -65,7 +65,11 @@ unsigned long arch_mmap_rnd(void) >> static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) >> { >> unsigned long gap = rlim_stack->rlim_cur; >> - unsigned long pad = (STACK_RND_MASK << PAGE_SHIFT) + stack_guard_gap; >> + unsigned long pad = stack_guard_gap; >> + >> + /* Account for stack randomization if necessary */ >> + if (current->flags & PF_RANDOMIZE) >> + pad += (STACK_RND_MASK << PAGE_SHIFT); >> >> /* Values close to RLIM_INFINITY can overflow. */ >> if (gap + pad > gap) >> -- >> 2.20.1 >> >