From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Thomas Fitzsimmons Newsgroups: gmane.emacs.bugs Subject: bug#63711: 30.0.50; Crash in xdisp.c when it->string is 0x0 Date: Thu, 25 May 2023 09:02:26 -0400 Message-ID: References: <83ilcgn9ud.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="38065"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Cc: 63711@debbugs.gnu.org To: Eli Zaretskii Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Thu May 25 15:03:39 2023 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1q2Ad0-0009dx-DE for geb-bug-gnu-emacs@m.gmane-mx.org; Thu, 25 May 2023 15:03:39 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1q2AcS-0006p3-J1; Thu, 25 May 2023 09:03:04 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1q2AcQ-0006nq-5N for bug-gnu-emacs@gnu.org; Thu, 25 May 2023 09:03:02 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1q2AcP-0006Hi-Sk for bug-gnu-emacs@gnu.org; Thu, 25 May 2023 09:03:01 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1q2AcP-0005im-Nn for bug-gnu-emacs@gnu.org; Thu, 25 May 2023 09:03:01 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Thomas Fitzsimmons Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Thu, 25 May 2023 13:03:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 63711 X-GNU-PR-Package: emacs Original-Received: via spool by 63711-submit@debbugs.gnu.org id=B63711.168501975521959 (code B ref 63711); Thu, 25 May 2023 13:03:01 +0000 Original-Received: (at 63711) by debbugs.gnu.org; 25 May 2023 13:02:35 +0000 Original-Received: from localhost ([127.0.0.1]:46235 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1q2Aby-0005i7-Vz for submit@debbugs.gnu.org; Thu, 25 May 2023 09:02:35 -0400 Original-Received: from mail.fitzsim.org ([69.165.165.189]:47350) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1q2Abx-0005ht-AO for 63711@debbugs.gnu.org; Thu, 25 May 2023 09:02:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=fitzsim.org ; s=20220430; h=Content-Type:MIME-Version:Message-ID:Date:References: In-Reply-To:Subject:Cc:To:From:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=QbDiE3wSgBomeJGo9nPiV3c53WKIDgG9Q90x5qL8e5I=; b=JBCJKpl8j2AMGf/BU+U1QYGL2B OZD9Y4K01Gl1SPQ5omPyHGbA4pQfkV9eRGKr43WPgesxI1ptB30kKDsE9cv4OEKfw3Rx056MqBAy0 6GZZjRgOMVFAA0+f/tCx5V66m1SB/3QEBLuA4UgFtB5tE7lIYNHrbuTqCsgMXQwQFjdx8ycvnMwDA 0pBn0UATqVjKDgUHOZN60wPnwsC4tQMwXkGojkC2iFUxPa4ZYMKJJxDnygs01bZoyXcNIFcWlMCO/ k9bCiULq6dwVE5HBqyw+LIwzxLl7P0ECpSb7xxYtt82IM53HdSP6K07GtobZdA3POhQyLNNmuHFBF e7sCZZ/A==; Original-Received: from [192.168.1.1] (helo=localhost.localdomain) by mail.fitzsim.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1q2Abr-000MuP-9c; Thu, 25 May 2023 09:02:27 -0400 In-Reply-To: <83ilcgn9ud.fsf@gnu.org> (Eli Zaretskii's message of "Thu, 25 May 2023 10:34:02 +0300") X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list 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-mx.org@gnu.org Original-Sender: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.bugs:262365 Archived-At: Hi Eli, Eli Zaretskii writes: >> From: Thomas Fitzsimmons >> Date: Thu, 25 May 2023 02:27:19 -0400 >> >> I have been having long-running Emacs sessions crash, rarely, and I >> finally caught one case in GDB. Full backtraces attached. I don't know >> how it->string becomes 0x0, but it looks like SCHARS (it->string) then >> attempts to dereference the null pointer. I'll keep the session running >> in case there is anything else someone wants me to check. > > Thanks, but with an optimized build and without a recipe to reproduce > this, it will be hard to debug this. Thanks for taking a look at this. Agreed it will be difficult. After this session I will rebuild Emacs with CFLAGS="-O0 -g" and run with GDB attached to try to get a higher quality trace. (The recipe to reproduce the crashes I've been seeing may be hard to obtain. I haven't identified any particular activity that triggers these crashes, and maybe there are different causes each time -- this is just the first one I captured.) > Still, I ask you below to produce some values from GDB in the hope > that this would give some ideas. OK: > (gdb) p pos->overlay_string_index $9 = 0 > (gdb) p it->current.overlay_string_index $10 = 0 > (gdb) p it->sp $11 = 0 > (gdb) p it->method $12 = GET_FROM_BUFFER > (gdb) p it->string $13 = XIL(0) > (gdb) xtype Lisp_Symbol The session is still open if you want me to check other values. Thanks, Thomas