From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: Preview: portable dumper Date: Tue, 29 Nov 2016 13:35:12 -0800 Organization: UCLA Computer Science Department Message-ID: <9b6a0571-b2ae-a5dd-a643-3595e8f71cd6@cs.ucla.edu> References: <047a67ec-9e29-7e4e-0fb0-24c3e59b5886@dancol.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: blaine.gmane.org 1480455361 920 195.159.176.226 (29 Nov 2016 21:36:01 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 29 Nov 2016 21:36:01 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 Cc: emacs-devel@gnu.org To: Daniel Colascione Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue Nov 29 22:35:52 2016 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cBq47-0007Q4-Kk for ged-emacs-devel@m.gmane.org; Tue, 29 Nov 2016 22:35:51 +0100 Original-Received: from localhost ([::1]:39367 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cBq4B-0008Ba-Bz for ged-emacs-devel@m.gmane.org; Tue, 29 Nov 2016 16:35:55 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:52779) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cBq3b-0008BJ-0V for emacs-devel@gnu.org; Tue, 29 Nov 2016 16:35:19 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cBq3X-0007I9-0H for emacs-devel@gnu.org; Tue, 29 Nov 2016 16:35:19 -0500 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:40316) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cBq3W-0007Hk-Pi for emacs-devel@gnu.org; Tue, 29 Nov 2016 16:35:14 -0500 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id A3861160129; Tue, 29 Nov 2016 13:35:13 -0800 (PST) Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id IGYpKmsPwiyi; Tue, 29 Nov 2016 13:35:13 -0800 (PST) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id F029816012B; Tue, 29 Nov 2016 13:35:12 -0800 (PST) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id V-kFPqJEEpNj; Tue, 29 Nov 2016 13:35:12 -0800 (PST) Original-Received: from Penguin.CS.UCLA.EDU (Penguin.CS.UCLA.EDU [131.179.64.200]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id D7F5D160129; Tue, 29 Nov 2016 13:35:12 -0800 (PST) In-Reply-To: X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 131.179.128.68 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:209772 Archived-At: On 11/29/2016 01:19 PM, Daniel Colascione wrote: > Even*with* a PIC Emacs (which I hope is the default, because ASLR > greatly improves security), we can get these savings if > mmap(BASE_ADDRESS_STORED_IN_DUMP, ...) succeeds and we can map the dump > where we want. If we can't map the dump where we want, we'll just > relocate it. Although your other advantages sound good, this one sounds worrisome. If Emacs maps the dump to the same place every time, we are giving up ASLR for the dump itself, and won't that pose a potential security risk? If so, perhaps it would be better to not mmap to the base address stored in the dump (unless we can determine that ASLR is not in use, I suppose).