Received: by 2002:a05:6a10:f347:0:0:0:0 with SMTP id d7csp744885pxu; Thu, 3 Dec 2020 11:30:00 -0800 (PST) X-Google-Smtp-Source: ABdhPJwnU9r6zgAkgtA80fXp7v8x9apXHKC1TWhvPNtTxNtVLYAnzN+2JwgdjXgkOy0XwKxKvvO3 X-Received: by 2002:a17:906:a195:: with SMTP id s21mr4055704ejy.146.1607023800763; Thu, 03 Dec 2020 11:30:00 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1607023800; cv=none; d=google.com; s=arc-20160816; b=cCkCrbpd1FUl52j0eiMvvDu5xpu0tCrB1+L99MNq+dht5AA4QRFUPFQ75AV45TerpJ 4wTqnzk656zmZzYsv1Bx681dHZEwDYkfUE5c5DoX6BNqVifkA+fUgclTVYgR4YnCKlwR jdO6uTxloe6okl1sTt+HvKuW/XTGpzB9oVUn8HI6SuExh1hUbhsyGaPGh8RKBdOfVqSI AF2gyb8Y2drYIapwt6RY13/C+BaHoxCu1Wp01LqRK1Akl1vsCK+OGJFipJlWe3BiGX/w wUDYBfDV3uYO41EkXXx0OhhR5KZQqx156ruEPDcrLaUCwsvNgVMOCjvjV6l3jXVxkDtu +3OQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:mime-version:user-agent:references:message-id :in-reply-to:subject:cc:to:from:date:ironport-sdr:ironport-sdr; bh=WE/x+0tiN3yFYSzYyRP4VuQD6LqwSOmC9rh7hnDY/+Y=; b=P/KivM7NedruNxRNTJ8DZ4BMbpndjqUawYgbj420CYlUttuuWJM9ty3dIQJ5tRtAgM FxgVHd6nbISDqdMvTIhGBFZiALHL1c4T5JE0SMr5xf2bXrmgEc5/eXD6VaXXd5ugTXav Z4WXWFVvhqILo57gmeXUL6S943kGP2nZc4h0o8WQnOzkh2ppL4NmY/fIZg92rs45P2ca FVZxyr+cr1weXX0R5a3rmN0J8C3ZRnCB5KmpUQ/ICyXqwCGi8x9PVgAnnZ/0rBxcVulk o88G4EvE1iFf90LrgpzOW6gBe1+sDie5vyh5kmiybXtke7UL2OOKeYpzLiVvnwTyI/td z55A== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id ec19si1706192ejb.669.2020.12.03.11.29.37; Thu, 03 Dec 2020 11:30:00 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726661AbgLCT13 (ORCPT + 99 others); Thu, 3 Dec 2020 14:27:29 -0500 Received: from esa4.mentor.iphmx.com ([68.232.137.252]:47459 "EHLO esa4.mentor.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726620AbgLCT12 (ORCPT ); Thu, 3 Dec 2020 14:27:28 -0500 IronPort-SDR: c5GQu1xkEhn8w8+YDEQYdRbJSxe5an2akUdHTSY1JJn2ByJ3naYEWgw2goiscJtnyRX6ijAXA7 nF9WF7KT9PWvLDCK7gZqQs6p0U+GiKEiixucaRAiwXslWV1bpYNUwApvFuO9N/g+p4c1VzPNCR ihx/cfEkwfsRlyDfR1+uZQoDeQpoJ7iX4yUFg2mc68hnbJU7Tx9MrTypzds7YMT46VZQQ18cnE SV2gzU/FBPZCBSifKhsG3U3x2W+OzTFAgSc2Y2lI1G9RhBTu4ojcXd9drpMeTesfWjiLHZeAUK t4Q= X-IronPort-AV: E=Sophos;i="5.78,390,1599552000"; d="scan'208";a="55902945" Received: from orw-gwy-02-in.mentorg.com ([192.94.38.167]) by esa4.mentor.iphmx.com with ESMTP; 03 Dec 2020 11:26:32 -0800 IronPort-SDR: XP3ZEQho3UqMx3BhYt1pQPTeKTRf5W8xIRihDvtCBy7QtU3tUhB7Phh67eaOt39ZLijARoJO73 cBW5k8t56e6WIOt9w363v7E0h1PB4g96rULSv/vrukcnALazLbg9LMKxWVlqSItIB4K6zGmnTz u7XrTyVwuFlmYBhsHPoIow3V9+KfZOiXyj+S61ioyEUkHp2VYVyzHPEoMsmwD+WGYEjTfayuI0 GzEBbFfSClbc3UwEsqiOgNjJiNBnBtWa04/aokI9hKNeV4uCNJjw9HpC2rb7Qk5jK+xs3yWoiY lis= Date: Thu, 3 Dec 2020 19:26:25 +0000 From: Joseph Myers X-X-Sender: jsm28@digraph.polyomino.org.uk To: Florian Weimer CC: Andy Lutomirski , Topi Miettinen , , , , , Jann Horn , Kees Cook , Matthew Wilcox , Mike Rapoport , Linux API Subject: Re: [PATCH v5] mm: Optional full ASLR for mmap(), mremap(), vdso and stack In-Reply-To: <871rg6yf1i.fsf@oldenburg2.str.redhat.com> Message-ID: References: <05D72EA3-4862-4D80-82F5-9369834C3461@amacapital.net> <871rg6yf1i.fsf@oldenburg2.str.redhat.com> User-Agent: Alpine 2.22 (DEB 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-Originating-IP: [137.202.0.90] X-ClientProxiedBy: SVR-IES-MBX-04.mgc.mentorg.com (139.181.222.4) To svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 3 Dec 2020, Florian Weimer wrote: > My knowledge of probability theory is quite limited, so I have to rely > on simulations. But I think you would see a 40 GiB gap somewhere for a > 47-bit address space with 32K allocations, most of the time. Which is > not too bad. This is very close to a Poisson process (if the number of small allocations being distributed independently in the address space is large), so the probability that any given gap is at least x times the mean gap is about exp(-x). -- Joseph S. Myers joseph@codesourcery.com