Bug in libX11 or something near ?

Bug in libX11 or something near ?

[Philippe]

Hello Cygwin list !

I'm using Cygwin/X and identified a critical bug using some piece of
software.
I don't really know where to begin, but I'm able to crash some applications
via the application's menu, only with Cygwin/X (no crash with Xming, and no
crash under any Linux distributions).

For information, It goes through VirtualGL. I'll give the example on how to
reproduce it with a free software : Paraview (under linux).

So you open Paraview, then clic on "View" > show the "Toolbars" submenu,
then you move your mouse directly on the "Sources" or "Edit" menu, then it
crashes immediately. The only error message in the linux shell (from where
it was launched) is "paraview: Fatal IO error: client killed".

I got those lines in the XWin.0.log file :
SetupSysMenu: GetSystemMenu() failed for HWND 0x130746
winTopLevelWindowProc - WM_DESTROY - WM_WM_KILL


I'm on the last available libX11, libxcb1 etc .

If you have any idea, thanks :)

Philippe

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Re: Bug in libX11 or something near ?

[Jon Turney]

On 18/06/2019 17:07, Philippe wrote:
> I'm using Cygwin/X and identified a critical bug using some piece of
> software.
> I don't really know where to begin, but I'm able to crash some applications
> via the application's menu, only with Cygwin/X (no crash with Xming, and no
> crash under any Linux distributions).
> 
> For information, It goes through VirtualGL. I'll give the example on how to
> reproduce it with a free software : Paraview (under linux).
> 
> So you open Paraview, then clic on "View" > show the "Toolbars" submenu,
> then you move your mouse directly on the "Sources" or "Edit" menu, then it
> crashes immediately. The only error message in the linux shell (from where
> it was launched) is "paraview: Fatal IO error: client killed".
> 
> I got those lines in the XWin.0.log file :
> SetupSysMenu: GetSystemMenu() failed for HWND 0x130746
> winTopLevelWindowProc - WM_DESTROY - WM_WM_KILL

Thanks for reporting this problem, and the clear reproduction steps.

This is an interesting bug in the Cygwin X server's multiwindow mode. It 
seems that under some circumstances, when removing a WM_TRANSIENT_FOR 
window which in turn had a child WM_TRANSIENT_FOR window (e.g. a menu 
which has a sub-menu), the X server's integrated WM would get confused 
and think that the main window had been closed (so terminating the 
application).

I've has a go at fixing this and uploaded a snapshot at [1].  Perhaps 
you could try that and see if it improves things for you?

(I guessed you are using 64-bit Cygwin. If you need a 32-bit build 
instead, please let me know and I'll generate one)

[1] 
ftp://cygwin.com/pub/cygwinx/x86_64/XWin.20190623-git-210c90b328cf8f18.exe.bz2

-- 
Jon Turney
Volunteer Cygwin/X X Server maintainer

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Re: Bug in libX11 or something near ?

[Philippe]

Hi Jon,
glad to view an answer !
Just for your information, since I posted, I did some others tests, and I
can reproduce it with k3b (which use qt4) but NOT with kcalc (which use
qt5).
Then I tried some little python tests from Envisage for qt5 and wasn't able
to reproduce this crash.

So I guess there's something wrong with qt4.

Tomorrow I'll try your snapshot to confirm or not your fix !

Thanks for your time.

On Sun, Jun 23, 2019 at 7:57 PM Jon Turney <jon.turney@dronecode.org.uk>
wrote:

> On 18/06/2019 17:07, Philippe wrote:
> > I'm using Cygwin/X and identified a critical bug using some piece of
> > software.
> > I don't really know where to begin, but I'm able to crash some
> applications
> > via the application's menu, only with Cygwin/X (no crash with Xming, and
> no
> > crash under any Linux distributions).
> >
> > For information, It goes through VirtualGL. I'll give the example on how
> to
> > reproduce it with a free software : Paraview (under linux).
> >
> > So you open Paraview, then clic on "View" > show the "Toolbars" submenu,
> > then you move your mouse directly on the "Sources" or "Edit" menu, then
> it
> > crashes immediately. The only error message in the linux shell (from
> where
> > it was launched) is "paraview: Fatal IO error: client killed".
> >
> > I got those lines in the XWin.0.log file :
> > SetupSysMenu: GetSystemMenu() failed for HWND 0x130746
> > winTopLevelWindowProc - WM_DESTROY - WM_WM_KILL
>
> Thanks for reporting this problem, and the clear reproduction steps.
>
> This is an interesting bug in the Cygwin X server's multiwindow mode. It
> seems that under some circumstances, when removing a WM_TRANSIENT_FOR
> window which in turn had a child WM_TRANSIENT_FOR window (e.g. a menu
> which has a sub-menu), the X server's integrated WM would get confused
> and think that the main window had been closed (so terminating the
> application).
>
> I've has a go at fixing this and uploaded a snapshot at [1].  Perhaps
> you could try that and see if it improves things for you?
>
> (I guessed you are using 64-bit Cygwin. If you need a 32-bit build
> instead, please let me know and I'll generate one)
>
> [1]
>
> ftp://cygwin.com/pub/cygwinx/x86_64/XWin.20190623-git-210c90b328cf8f18.exe.bz2
>
> --
> Jon Turney
> Volunteer Cygwin/X X Server maintainer
>

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Re: Bug in libX11 or something near ?

[Philippe]

Hi Jon,
I just tested your snapshot on some software (including k3b, paraview and
some others), and no more crashes !

Thanks a lot for this fix :)

I guess you can release it on cygwin asap !

Thanks again for this fast work.

regards,
Philippe

On Sun, Jun 23, 2019 at 8:41 PM Philippe <philippe.raven@gmail.com> wrote:

> Hi Jon,
> glad to view an answer !
> Just for your information, since I posted, I did some others tests, and I
> can reproduce it with k3b (which use qt4) but NOT with kcalc (which use
> qt5).
> Then I tried some little python tests from Envisage for qt5 and wasn't
> able to reproduce this crash.
>
> So I guess there's something wrong with qt4.
>
> Tomorrow I'll try your snapshot to confirm or not your fix !
>
> Thanks for your time.
>
> On Sun, Jun 23, 2019 at 7:57 PM Jon Turney <jon.turney@dronecode.org.uk>
> wrote:
>
>> On 18/06/2019 17:07, Philippe wrote:
>> > I'm using Cygwin/X and identified a critical bug using some piece of
>> > software.
>> > I don't really know where to begin, but I'm able to crash some
>> applications
>> > via the application's menu, only with Cygwin/X (no crash with Xming,
>> and no
>> > crash under any Linux distributions).
>> >
>> > For information, It goes through VirtualGL. I'll give the example on
>> how to
>> > reproduce it with a free software : Paraview (under linux).
>> >
>> > So you open Paraview, then clic on "View" > show the "Toolbars" submenu,
>> > then you move your mouse directly on the "Sources" or "Edit" menu, then
>> it
>> > crashes immediately. The only error message in the linux shell (from
>> where
>> > it was launched) is "paraview: Fatal IO error: client killed".
>> >
>> > I got those lines in the XWin.0.log file :
>> > SetupSysMenu: GetSystemMenu() failed for HWND 0x130746
>> > winTopLevelWindowProc - WM_DESTROY - WM_WM_KILL
>>
>> Thanks for reporting this problem, and the clear reproduction steps.
>>
>> This is an interesting bug in the Cygwin X server's multiwindow mode. It
>> seems that under some circumstances, when removing a WM_TRANSIENT_FOR
>> window which in turn had a child WM_TRANSIENT_FOR window (e.g. a menu
>> which has a sub-menu), the X server's integrated WM would get confused
>> and think that the main window had been closed (so terminating the
>> application).
>>
>> I've has a go at fixing this and uploaded a snapshot at [1].  Perhaps
>> you could try that and see if it improves things for you?
>>
>> (I guessed you are using 64-bit Cygwin. If you need a 32-bit build
>> instead, please let me know and I'll generate one)
>>
>> [1]
>>
>> ftp://cygwin.com/pub/cygwinx/x86_64/XWin.20190623-git-210c90b328cf8f18.exe.bz2
>>
>> --
>> Jon Turney
>> Volunteer Cygwin/X X Server maintainer
>>
>

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Re: Bug in libX11 or something near ?

[Jon Turney]

On 24/06/2019 08:28, Philippe wrote:
> Hi Jon,
> I just tested your snapshot on some software (including k3b, paraview and
> some others), and no more crashes !

Great.  Thanks for testing.

> Thanks a lot for this fix :)
> 
> I guess you can release it on cygwin asap !

Assuming it doesn't break something else...

This fix is in the 1.20.5-2 test release.

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