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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id DD38BC4706C for ; Tue, 16 Jan 2024 08:10:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 77F8D6B0075; Tue, 16 Jan 2024 03:10:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 72F9B6B0078; Tue, 16 Jan 2024 03:10:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5F9406B007B; Tue, 16 Jan 2024 03:10:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 4C0ED6B0075 for ; Tue, 16 Jan 2024 03:10:17 -0500 (EST) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 2A538160778 for ; Tue, 16 Jan 2024 08:10:17 +0000 (UTC) X-FDA: 81684451674.08.B028886 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by imf04.hostedemail.com (Postfix) with ESMTP id D0B3F40002 for ; Tue, 16 Jan 2024 08:10:14 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=r4HAnD2t; spf=pass (imf04.hostedemail.com: domain of ardb@kernel.org designates 145.40.73.55 as permitted sender) smtp.mailfrom=ardb@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1705392615; a=rsa-sha256; cv=none; b=hdp9inmpPALXHcfcVLPkY/7K3xyGpTclnO6Ck+spoBoxrTYWbWVqYvvqbHhcZI29ObUVgk JYTVaLEKlb6hXSKnem+Udc71GZbb+wZa0zxjdIg6F5zIm5BS9nL5QSNx8coYDPEDxHfvwH PbApWNaEQX4udNbmuHzdpFs+ltZ9NQo= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=r4HAnD2t; spf=pass (imf04.hostedemail.com: domain of ardb@kernel.org designates 145.40.73.55 as permitted sender) smtp.mailfrom=ardb@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1705392615; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=IT+TIjL1CrPhycq+yTnX4EYNZs5F4vAUjuXT71VhKXc=; b=VonfkSlbsfuYAoeP6Qz/oc+9RlloHeBEEQQx4obVkxT0z70abasaeONvYiW2Ko68k3f/ph srFFtPpAajSWydNxXsjWr/+EesPUASoRpDBh90airXL9P/Ybhb99oS8cII3pk78djPnB0W iMGi3nRMGA+Vfu/YJTE3iox3i64ia44= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 0F9FCCE18CE for ; Tue, 16 Jan 2024 08:10:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2C2AFC433F1 for ; Tue, 16 Jan 2024 08:09:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1705392599; bh=byEKLkL6nYz7FHH2I12EM71SKWmMWcc1bETeEol6Nxk=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=r4HAnD2tFj202U7I+5EFgguOsA8FSAHv/HGpSFqSbrEQyCkT6AvkCvHFCjXBuC4QM 4VLJxiU8e7dlS239FpbZ5U/VuHRHZoUSsBYSwgie+i2Zn2onAJb4rncGlqIcWM8vgH ToOvp+3WAsTzvepf5kA6Yj/ip7zbxoqD1tgzh13cXS68I8h9WCfFDMYPmy3EpQlC8d nNg+ZJBjIJVsBvVKcZC2XGcROGcZBHXoGI5tmV+0Pm6mePTaOFFTbU+cRpH/dIeGeo in7Rks8JWtgVi+3bl60uJFbZG/QVmK+i4lQzPBmEUOtOvBOsfRZek0uGm7ZLCQPXKG m9rZsIJOC5Rvg== Received: by mail-lf1-f52.google.com with SMTP id 2adb3069b0e04-50e7c6e3c63so9884563e87.3 for ; Tue, 16 Jan 2024 00:09:59 -0800 (PST) X-Gm-Message-State: AOJu0YwiqFKmAcbMjsc94LjYrIHY5rsT13dOF1LNCZbXN0sbs7jFQOn8 PK4yM6E3S4kZrN9o2+buOC6faGgSmlL/1D8RACQ= X-Google-Smtp-Source: AGHT+IERnctLPAujSEvr6b4uRVZ0JCeFDQ8suHcX9nEcAJU+PGBTdUwP/SllPYMSFKZrJPyzpHfW0BVCrb0X+bIohWY= X-Received: by 2002:a19:8c17:0:b0:50e:b2aa:1f23 with SMTP id o23-20020a198c17000000b0050eb2aa1f23mr1515635lfd.144.1705392597375; Tue, 16 Jan 2024 00:09:57 -0800 (PST) MIME-Version: 1.0 References: <69fa6015256613ed10aee996e181ebd4@horotw.com> <87il3ur1ik.fsf@gentoo.org> <07c348caaf6b4c457ab4b452f53ed048@horotw.com> In-Reply-To: From: Ard Biesheuvel Date: Tue, 16 Jan 2024 09:09:45 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: Limited/Broken functionality of ASLR for Libs >= 2MB To: Matthew Wilcox , Kees Cook , Linux ARM Cc: mail@horotw.com, linux-hardening@vger.kernel.org, Jakub Wilk , Salvatore Bonaccorso , Linux Memory Management List , William Kucharski Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: D0B3F40002 X-Stat-Signature: qa988o4a47ktsh3arkfzybwypzx7mfmz X-Rspam-User: X-HE-Tag: 1705392614-51574 X-HE-Meta: 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 HnKvXYwx JAGpBovprBR6QJuzQXyI+lH72yF/hwvqiQ1pCIVFi29IYj+QYf8VCu3DP1f2EVzUWppWrNQumQPU3l6v1n2VOrwgWM0WGUPOD/UA86P09SWt45N18XGP7SbjF1dpG1MIe8H/j3qtFfMf71mH75fW8ZFP4zuswED2xZXR/lB7DHKcSRIQaA1dLJ9vKN+PBGsUyKIFZ1MOL7TAcriDZTR2dc/wg0yc8ZsopJIlSufRenp9gNoWbqkYNUdApn2bZUB7aY/cftPcybo2MOnoxmFn+uLF+qE6UFqu9SSvbdiaZMg59rg5kcYtzaNRONvEuYpUQeVIIxlk+0J8rD/cNthxk2Q6Gc8ZSbjHJ6A8stQmXvbIF3eDbsl4eaem28dL7fO8yyZoBGBrYZ8kY1mmtGvyKDPHPfl1xYLpxnkHy X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: (cc Kees, LAKML) https://lkml.kernel.org/r/69fa6015256613ed10aee996e181ebd4%40horotw.com On Mon, 15 Jan 2024 at 21:46, Matthew Wilcox wrote: > ... > Yeah, I don't know either. Outside my scope of expertise. > > I received a suggestion off-list that we only do the PMD alignment on > 64-bit, which seems quite reasonable to me. After all, I don't care > about performance on 32-bit just as much as I don't care about security > on 32-bit. > For context, the culprit is commit 1854bc6e2420472676c5c90d3d6b15f6cd640e40 Author: William Kucharski Date: Sun Sep 22 08:43:15 2019 -0400 mm/readahead: Align file mappings for non-DAX When we have the opportunity to use PMDs to map a file, we want to follow the same rules as DAX. Signed-off-by: William Kucharski Signed-off-by: Matthew Wilcox (Oracle) which affects *all* 32-bit architectures not just i686. 32-bit ARM user space is still being deployed widely, even on arm64 Chromebooks running 64-bit kernels (at least up until recently) so unfortunately, we're not quite at the point yet where we can just let it rot.