GNU bug report logs - #6284
Crash in w32_wnd_proc at frame deletion

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Lennart Borgman <lennart.borgman <at> gmail.com>
To: Emacs Bugs <bug-gnu-emacs <at> gnu.org>
Subject: Crash in w32_wnd_proc at frame deletion
Date: Thu, 27 May 2010 19:44:27 +0200

Now I finally got a backtrace of this crash. Thanks for the (harsh)
reminders about running under gdb.

Here is part of the backtrace

  Program received signal SIGSEGV, Segmentation fault.
  [Switching to Thread 1836.0xef8]
  0x011cc376 in w32_wnd_proc (hwnd=0x1001ac, msg=32, wParam=1049004,
      lParam=33554433) at w32fns.c:4351
  4351              if (f->output_data.w32->hourglass_p && !menubar_in_use
  (gdb) bt
  #0  0x011cc376 in w32_wnd_proc (hwnd=0x1001ac, msg=32, wParam=1049004,
      lParam=33554433) at w32fns.c:4351
  #1  0x7e418734 in USER32!GetDC () from C:\WINDOWS\system32\user32.dll
  #2  0x001001ac in ?? ()
  #3  0x00000020 in ?? ()
  #4  0x001001ac in ?? ()
  #5  0x02000001 in ?? ()
  #6  0x011c9291 in post_character_message (hwnd=0x11c9291, msg=1049004,
      wParam=32, lParam=1049004, dwmodifiers=33554433) at w32fns.c:3049
  #7  0x7e418816 in USER32!GetDC () from C:\WINDOWS\system32\user32.dll
  #8  0x011c9291 in post_character_message (hwnd=0x0, msg=18649745,
      wParam=1049004, lParam=32, dwmodifiers=1049004) at w32fns.c:3049
  #9  0x7e428ea0 in USER32!DefWindowProcW () from C:\WINDOWS\system32\user32.dll
  #10 0x00000000 in ?? ()

  Lisp Backtrace:
  "delete-frame" (0x82af44)

It looks like the important part is line 4351. I tried to look at f:

  (gdb) print f
  $1 = (struct frame *) 0x0
  (gdb) print f->output_data
  Cannot access memory at address 0x104

Does this mean that f might be gone here and that there should be a
test for this?

Message #8 received at 6284 <at> debbugs.gnu.org (full text, mbox):

From: Juanma Barranquero <lekktu <at> gmail.com>
To: Lennart Borgman <lennart.borgman <at> gmail.com>
Cc: 6284 <at> debbugs.gnu.org
Subject: Re: bug#6284: Crash in w32_wnd_proc at frame deletion
Date: Thu, 27 May 2010 20:26:22 +0200

On Thu, May 27, 2010 at 19:44, Lennart Borgman
<lennart.borgman <at> gmail.com> wrote:

> Now I finally got a backtrace of this crash. Thanks for the (harsh)
> reminders about running under gdb.

More like "stern" :-)

> Here is part of the backtrace

Is that with an optimized or non-optimized build?

Is the crash repeatable at will?

    Juanma

Message #11 received at 6284 <at> debbugs.gnu.org (full text, mbox):

From: Lennart Borgman <lennart.borgman <at> gmail.com>
To: Juanma Barranquero <lekktu <at> gmail.com>
Cc: 6284 <at> debbugs.gnu.org
Subject: Re: bug#6284: Crash in w32_wnd_proc at frame deletion
Date: Thu, 27 May 2010 20:34:40 +0200

On Thu, May 27, 2010 at 8:26 PM, Juanma Barranquero <lekktu <at> gmail.com> wrote:
> On Thu, May 27, 2010 at 19:44, Lennart Borgman
> <lennart.borgman <at> gmail.com> wrote:
>
>> Now I finally got a backtrace of this crash. Thanks for the (harsh)
>> reminders about running under gdb.
>
> More like "stern" :-)

My English does not know that.

>> Here is part of the backtrace
>
> Is that with an optimized or non-optimized build?

Non-optimized.

> Is the crash repeatable at will?

Maybe, but I do not know whose will. I know how it happens, but not when.

Anyway, I mailed Eli and asked him immediately since I feared my pc
might hang (which it can do sometimes when bugs jumps in). Thee is a
bug in w32fns.c where this happened. There should be a check if f is
0.

There seems to be more places where this is not checked. I will look
through them and add a patch here.

Message #14 received at 6284 <at> debbugs.gnu.org (full text, mbox):

From: Lennart Borgman <lennart.borgman <at> gmail.com>
To: Juanma Barranquero <lekktu <at> gmail.com>, Eli Zaretskii <eliz <at> gnu.org>
Cc: 6284 <at> debbugs.gnu.org
Subject: Re: bug#6284: Crash in w32_wnd_proc at frame deletion
Date: Fri, 28 May 2010 00:33:49 +0200

[Message part 1 (text/plain, inline)]

On Thu, May 27, 2010 at 8:34 PM, Lennart Borgman
<lennart.borgman <at> gmail.com> wrote:
>
> There is a
> bug in w32fns.c where this happened. There should be a check if f is
> 0.
>
> There seems to be more places where this is not checked. I will look
> through them and add a patch here.

I have attached a patch. Please review it and install it.

[bug6284-1.diff (text/x-patch, attachment)]

Message #17 received at 6284 <at> debbugs.gnu.org (full text, mbox):

From: Lennart Borgman <lennart.borgman <at> gmail.com>
To: Juanma Barranquero <lekktu <at> gmail.com>, Eli Zaretskii <eliz <at> gnu.org>
Cc: 6284 <at> debbugs.gnu.org
Subject: Re: bug#6284: Crash in w32_wnd_proc at frame deletion
Date: Sat, 29 May 2010 01:44:01 +0200

[Message part 1 (text/plain, inline)]

New patch. I missed one place in the previous patch and this just hit me.

It is great running under the debugger and finally being able to find
and fix those bugs I have wondered about quite long now but have not
had time to fix before.

The only problem now is how to get them installed. As I said elsewhere
I currently have no checkout from savannah so I can't checkin the
patches myself AFAIK. Should I get a second checkout from savannah for
this, or?

[bug6284-2.diff (text/x-patch, attachment)]

Message #22 received at 6284-done <at> debbugs.gnu.org (full text, mbox):

From: Jason Rumney <jasonr <at> gnu.org>
To: Lennart Borgman <lennart.borgman <at> gmail.com>
Cc: Juanma Barranquero <lekktu <at> gmail.com>, Eli Zaretskii <eliz <at> gnu.org>,
	6284-done <at> debbugs.gnu.org
Subject: Re: bug#6284: Crash in w32_wnd_proc at frame deletion
Date: Fri, 08 Jul 2011 20:53:47 +0800

Lennart Borgman <lennart.borgman <at> gmail.com> writes:

> New patch. I missed one place in the previous patch and this just hit me.
>
> It is great running under the debugger and finally being able to find
> and fix those bugs I have wondered about quite long now but have not
> had time to fix before.
>
> The only problem now is how to get them installed. As I said elsewhere
> I currently have no checkout from savannah so I can't checkin the
> patches myself AFAIK. Should I get a second checkout from savannah for
> this, or?

I fixed the two locations where a bug could conceivably occur.  Others
were either #ifdef'ed out, or already protected against dereferencing
the non-existent frame struct.

Message #23 received at 6284-done <at> debbugs.gnu.org (full text, mbox):

From: Lennart Borgman <lennart.borgman <at> gmail.com>
To: Jason Rumney <jasonr <at> gnu.org>
Cc: Juanma Barranquero <lekktu <at> gmail.com>, Eli Zaretskii <eliz <at> gnu.org>,
	6284-done <at> debbugs.gnu.org
Subject: Re: bug#6284: Crash in w32_wnd_proc at frame deletion
Date: Fri, 8 Jul 2011 16:19:01 +0200

On Fri, Jul 8, 2011 at 14:53, Jason Rumney <jasonr <at> gnu.org> wrote:
> Lennart Borgman <lennart.borgman <at> gmail.com> writes:
>
>> New patch. I missed one place in the previous patch and this just hit me.
>>
>> It is great running under the debugger and finally being able to find
>> and fix those bugs I have wondered about quite long now but have not
>> had time to fix before.
>>
>> The only problem now is how to get them installed. As I said elsewhere
>> I currently have no checkout from savannah so I can't checkin the
>> patches myself AFAIK. Should I get a second checkout from savannah for
>> this, or?
>
> I fixed the two locations where a bug could conceivably occur.  Others
> were either #ifdef'ed out, or already protected against dereferencing
> the non-existent frame struct.

Thanks.

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