From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Richard Stallman Newsgroups: gmane.emacs.devel Subject: Re: Stack clobbering bug Date: Fri, 21 Jul 2006 15:36:58 -0400 Message-ID: References: Reply-To: rms@gnu.org NNTP-Posting-Host: main.gmane.org Content-Type: text/plain; charset=ISO-8859-15 X-Trace: sea.gmane.org 1153510650 26638 80.91.229.2 (21 Jul 2006 19:37:30 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Fri, 21 Jul 2006 19:37:30 +0000 (UTC) Cc: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Jul 21 21:37:27 2006 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by ciao.gmane.org with esmtp (Exim 4.43) id 1G40oE-0002SG-JD for ged-emacs-devel@m.gmane.org; Fri, 21 Jul 2006 21:37:14 +0200 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1G40oD-0005LI-Vd for ged-emacs-devel@m.gmane.org; Fri, 21 Jul 2006 15:37:13 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1G40o1-0005KR-J2 for emacs-devel@gnu.org; Fri, 21 Jul 2006 15:37:01 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1G40o0-0005Jh-9f for emacs-devel@gnu.org; Fri, 21 Jul 2006 15:37:00 -0400 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1G40nz-0005JL-WA for emacs-devel@gnu.org; Fri, 21 Jul 2006 15:37:00 -0400 Original-Received: from [199.232.76.164] (helo=fencepost.gnu.org) by monty-python.gnu.org with esmtp (Exim 4.52) id 1G40oT-0005KD-Fs for emacs-devel@gnu.org; Fri, 21 Jul 2006 15:37:29 -0400 Original-Received: from rms by fencepost.gnu.org with local (Exim 4.34) id 1G40ny-0007ta-TZ; Fri, 21 Jul 2006 15:36:58 -0400 Original-To: Thien-Thi Nguyen In-reply-to: (message from Thien-Thi Nguyen on 21 Jul 2006 04:53:55 -0400) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:57439 Archived-At: #2 0x00800040 in ?? () Cannot access memory at address 0x40038 That "Cannot access memory" suggests that the stack is clobbered. On some platforms, with some kinds of optimization, there is no frame pointer and chasing the stack requires some additional info. However, aside from such cases, the lack of debug info for a library should not stop GDB from finding and displaying further frames. So I think the stack is clobbered, as it was in my case. i haven't looked further. what is a good way to get more useful info than this from gdb? The first thing to do is x/20xw $sp and then repeat x/20xw a few times to see if part of the stack is clobbered with -1. However, I suspect that the way to debug this is to try the sources from various different dates, and determine which change made the problem start to happen.