DMARC-Filter:	OpenDMARC Filter v1.4.2 delorie.com 54GBkuVj3937656
Authentication-Results:	delorie.com; dmarc=pass (p=none dis=none) header.from=cygwin.com
Authentication-Results:	delorie.com; spf=pass smtp.mailfrom=cygwin.com
DKIM-Filter:	OpenDKIM Filter v2.11.0 delorie.com 54GBkuVj3937656
Authentication-Results:	delorie.com;
	dkim=pass (1024-bit key, unprotected) header.d=cygwin.com header.i=@cygwin.com header.a=rsa-sha256 header.s=default header.b=XeMLF/44
X-Recipient:	archive-cygwin AT delorie DOT com
DKIM-Filter:	OpenDKIM Filter v2.11.0 sourceware.org 39A1A3857737
DKIM-Signature:	v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
	s=default; t=1747396014;
	bh=DmNkBmIWrvYZEdP8RRIjlHm3unFk9jArRC9qIomvEds=;
	h=Subject:To:Date:List-Id:List-Unsubscribe:List-Archive:List-Post:
	List-Help:List-Subscribe:From:Reply-To:Cc:From;
	b=XeMLF/44PReQFhOf8RMMqkIbr7tmgFvt8x+ecLmKuaLzqMFxkXtjAW8CQ368zphv/
	tEJ4qD/nMWXDzpvGamz80k0fGH1syCtNu2wjISqhkmuq/DE3jnlWaGJHKjLTle/SCY
	Nt9AuTvP6GuqMndcFYUicUlY+PdpkgZPk49tFgYY=
X-Original-To:	cygwin AT cygwin DOT com
Delivered-To:	cygwin AT cygwin DOT com
DMARC-Filter:	OpenDMARC Filter v1.4.2 sourceware.org 327BC385841C
ARC-Filter:	OpenARC Filter v1.0.0 sourceware.org 327BC385841C
ARC-Seal:	i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1747395986; cv=none;
	b=FNHfa1DtR+KrqQjSNEhVVBYWly2N090ugLUpIymRVL6GbDBAtYPdg6g3EfaWQ75+ygHjKZAAE+7E749A9vdzNgMTSqSD0nrpbrKAQ3Gr5NLtsd9unIAUHuNwW1gI/tpdriS/1M2Ei/3BuXSNYV2HkbaIQKY2o9wEjHWJSVZGIt8=
ARC-Message-Signature:	i=1; a=rsa-sha256; d=sourceware.org; s=key;
	t=1747395986; c=relaxed/simple;
	bh=lca78r11h6HXkZgCBVUSW8EWPuAI9VeEo9v/N0a+/2Y=;
	h=From:Subject:To:Message-ID:Date:MIME-Version;
	b=SiyfOmxMbpj04t54rwh4wYlVRFZCUYHsLXcjx6gmjtiDSrJ+RXxWFm5zJcZB8cfhbWzeUEnKU2zt401gSzEZn4eDCzKJtQDL4sX+LkfWDPouwt9GYhybroZfjjbKVt1HnLmYv7A7n//S9CbD/D3rsrcTrUysox3eSXeMe1FoU80=
ARC-Authentication-Results:	i=1; server2.sourceware.org
DKIM-Filter:	OpenDKIM Filter v2.11.0 sourceware.org 327BC385841C
Subject:	strace: infinite exception c0000005 loop on segmentation fault
To:	cygwin AT cygwin DOT com
Message-ID:	<320ee4eb-a06d-150d-ef12-3dc501bbd60b@t-online.de>
Date:	Fri, 16 May 2025 13:46:21 +0200
User-Agent:	Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:128.0) Gecko/20100101
	SeaMonkey/2.53.20
MIME-Version:	1.0
X-TOI-EXPURGATEID:	150726::1747395981-4FFFD4E5-70AAF359/0/0 CLEAN NORMAL
X-TOI-MSGID:	aa2f5b2c-9aa5-49ef-8bd3-f00fda3d7052
X-BeenThere:	cygwin AT cygwin DOT com
X-Mailman-Version:	2.1.30
List-Id:	General Cygwin discussions and problem reports <cygwin.cygwin.com>
List-Archive:	<https://cygwin.com/pipermail/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-request AT cygwin DOT com?subject=help>
List-Subscribe:	<https://cygwin.com/mailman/listinfo/cygwin>,
	<mailto:cygwin-request AT cygwin DOT com?subject=subscribe>
From:	Christian Franke via Cygwin <cygwin AT cygwin DOT com>
Reply-To:	cygwin AT cygwin DOT com
Cc:	Christian Franke <Christian DOT Franke AT t-online DOT de>
Sender:	"Cygwin" <cygwin-bounces~archive-cygwin=delorie DOT com AT cygwin DOT com>
X-MIME-Autoconverted:	from base64 to 8bit by delorie.com id 54GBkuVj3937656

Found during check why SIGSEGV handler could interrupt SIGALRM handler 
(which does not happen on Linux):
https://sourceware.org/pipermail/cygwin-patches/2025q2/013703.html

Testcase:

$ uname -r # Also occurs with 3.6.1-1.x86_64
3.7.0-0.95.g854150fda310.x86_64

$ cat sigsegv.c
int main()
{
   *(volatile char *)0 = 0;
   return 42; // NOTREACHED
}

$ gcc -o sigsegv sigsegv.c

$ ./sigsegv # OK
Segmentation fault

$ echo $?
139

$ (sleep 5; taskkill /f /im strace.exe) & strace ./sigsegv # Infinite loop
...
--- Process 11224 (pid: 2162), exception c0000005 at 0000000100401092
--- Process 11224 (pid: 2162), exception c0000005 at 0000000100401092
--- Process 11224 (pid: 2162), exception c0000005 at 0000000100401092
--- Process 11224 (pid: 2162), exception c0000005 at 0000000100401092
--- Process 11224 (pid: 2162), exception c0000005 at 0000000100401092
--- Process 11224 (pid: 2162), exception c0000005 at 0000000100401092
--- Process 11224 (pid: 2162), exception c0000005 at 0000000100401092
--- Process 11224 (pid: 2162), exception c0000005 at 0000000
SUCCESS: ... (localized message from taskkill)


The problem also occurs if a SIGSEGV handler is present. The handler 
code is not executed if strace is used but works as expected without strace.

-- 
Regards,
Christian


-- 
Problem reports:      https://cygwin.com/problems.html
FAQ:                  https://cygwin.com/faq/
Documentation:        https://cygwin.com/docs.html
Unsubscribe info:     https://cygwin.com/ml/#unsubscribe-simple

- Raw text -