From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.bugs Subject: bug#18410: Use SAFE_ALLOCA etc. to avoid unbounded stack allocation. Date: Sun, 07 Sep 2014 19:38:17 -0700 Organization: UCLA Computer Science Department Message-ID: <540D1699.2030903@cs.ucla.edu> References: <5409536B.5090201@cs.ucla.edu> <540C0741.8090900@cs.ucla.edu> <83bnqrcq7u.fsf@gnu.org> <540CC106.8040705@cs.ucla.edu> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1410143968 28781 80.91.229.3 (8 Sep 2014 02:39:28 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 8 Sep 2014 02:39:28 +0000 (UTC) Cc: 18410@debbugs.gnu.org To: Stefan Monnier Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Mon Sep 08 04:39:20 2014 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XQorQ-0001ah-Hn for geb-bug-gnu-emacs@m.gmane.org; Mon, 08 Sep 2014 04:39:20 +0200 Original-Received: from localhost ([::1]:40313 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XQorQ-0007fl-6p for geb-bug-gnu-emacs@m.gmane.org; Sun, 07 Sep 2014 22:39:20 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:48883) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XQorG-0007dt-F6 for bug-gnu-emacs@gnu.org; Sun, 07 Sep 2014 22:39:17 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XQor8-0005KQ-T5 for bug-gnu-emacs@gnu.org; Sun, 07 Sep 2014 22:39:10 -0400 Original-Received: from debbugs.gnu.org ([140.186.70.43]:41551) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XQor8-0005KL-Pf for bug-gnu-emacs@gnu.org; Sun, 07 Sep 2014 22:39:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.80) (envelope-from ) id 1XQor8-0000rw-GK for bug-gnu-emacs@gnu.org; Sun, 07 Sep 2014 22:39:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Paul Eggert Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Mon, 08 Sep 2014 02:39:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 18410 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: patch Original-Received: via spool by 18410-submit@debbugs.gnu.org id=B18410.14101439183311 (code B ref 18410); Mon, 08 Sep 2014 02:39:02 +0000 Original-Received: (at 18410) by debbugs.gnu.org; 8 Sep 2014 02:38:38 +0000 Original-Received: from localhost ([127.0.0.1]:33115 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.80) (envelope-from ) id 1XQoqk-0000rL-2v for submit@debbugs.gnu.org; Sun, 07 Sep 2014 22:38:38 -0400 Original-Received: from smtp.cs.ucla.edu ([131.179.128.62]:42490) by debbugs.gnu.org with esmtp (Exim 4.80) (envelope-from ) id 1XQoqg-0000r3-II for 18410@debbugs.gnu.org; Sun, 07 Sep 2014 22:38:35 -0400 Original-Received: from localhost (localhost.localdomain [127.0.0.1]) by smtp.cs.ucla.edu (Postfix) with ESMTP id C55B4A60005; Sun, 7 Sep 2014 19:38:26 -0700 (PDT) X-Virus-Scanned: amavisd-new at smtp.cs.ucla.edu Original-Received: from smtp.cs.ucla.edu ([127.0.0.1]) by localhost (smtp.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id pI0LZm0ukiql; Sun, 7 Sep 2014 19:38:18 -0700 (PDT) Original-Received: from [192.168.1.9] (pool-71-177-17-123.lsanca.dsl-w.verizon.net [71.177.17.123]) by smtp.cs.ucla.edu (Postfix) with ESMTPSA id 15DA239E8011; Sun, 7 Sep 2014 19:38:18 -0700 (PDT) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 In-Reply-To: X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.15 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 140.186.70.43 X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Original-Sender: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.bugs:93129 Archived-At: Stefan Monnier wrote: > MAX_ALLOCA is chosen small so that we can allocate several/many objects > of size MAX_ALLOCA. That's one reason, but another is that stack-overflow checking often relies on guard pages. If we blindly increase MAX_ALLOCA (or some variant of it, just for call-process) Emacs could bypass stack-overflow checking, resulting in behavior that could be worse than simply dumping core. If I understand things correctly, Dmitry's recent stack-overflow changes don't affect this, as they don't deal with the guard-page region size.