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Date: Thu, 16 Aug 2012 20:20:37 +0400
Message-ID: <CACgPhYoVzcUEH-w1Lx5zgwbY-Jic67sH=gwy2qGiqMrv519sOA@mail.gmail.com>
Subject: Re: Cygwin crashes in kill_pgrp, _pinfo truncation issue.
From: Andrey Khalyavin <halyavin AT google DOT com>
To: cygwin AT cygwin DOT com
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On Wed, 15 Aug 2012 10:11:16 -0400, Christopher Faylor wrote:
>On Wed, Aug 15, 2012 at 04:54:42PM +0400, Andrey Khalyavin wrote:
>>I finally got a cygwin crash dump from our build bots. It shows, that
>>cygwin1.dll crashes in kill_pgrp function on line:
>>	  (pid > 1 && p->pgid != pid) ||
>>where p is a pointer to _pinfo. This function enumerates all _pinfo's
>>and executes this line for all of them which pass p->exists() check.
>>In crash dump p points to _pinfo that has process_state equal to
>>PID_IN_USE | PID_EXECED.
>
>Thanks for tracking this down.  I've added a check for "execed" to
>_pinfo::exists.
>
>cgf
I updated core libraries from 20120803 snapshot to 20120815 snapshot
and now bash crashes when I execute rm -rf dir. Reproducibility is
strange. It crashed for hours when I entered
cd /tmp
mkdir a
rm -rf a
commands but now suddenly stopped crashing in this case.
It is still crashes on rm -rf in the real script we use though.

Crash happens in setup_handler function on line
	  HANDLE hth = (HANDLE) *tls;
because tls->tid equals to zero. Definition of this operation is in
sygtls.h: operator HANDLE () const {return tid->win32_obj_id;}.
setup_handler is called from sigpacket::process which in turn
called from wait_sig. Signal number is 20, signal code is 28.
All fields of tls structure are zero with exception stacklock equal
to 1 and stackptr equal to address of tls->stack.

I don't understand what goes wrong here. Can you suggest what
I can look for in the debugger?

Andrey Khalyavin

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