Re: [XForms] Problem with fdesign (fdesigns menu bar) (fwd)

[Michal Szymanski]

I have followed 'popup.c' file usage pattern:

    if ( popup->title )
        XStoreName( flx->display, popup->win, popup->title );

and modified 'xpopup.c' accordingly:

-       XStoreName( flx->display, m->win, m->title );
+       if ( m->title )
+         XStoreName( flx->display, m->win, m->title );

and it seems to have fixed the problem.

Interestingly, on MX-21 Linux (based on Debian 11), fdesign built on
Git code works fine w/o any modifications. The system has xserver-xorg
version 1.20.13-1~mx21ahs+1 (compared to 1.20.13-1ubuntu1~20.04.2 in
Ubuntu 20.04 and 1.20.11-2 in Rocky Linux 8.5)

regards,
Michal

On Thu, May 12, 2022 at 04:01:48PM +0100, Clive Stubbings wrote:
> Try
> 
> -       XStoreName(flx->display, m->win, m->title);
> +       XStoreName(flx->display, m->win, m->title ? m->title : "");
> 
> Cheers
> Clive
> 
> On Thu, 12 May 2022, Michal Szymanski wrote:
> 
> >I have built the current git version
> >(https://git.savannah.gnu.org/git/xforms.git) on Ubuntu 20.04 and
> >Rocky Linux 8.5 and got the same problem: fdesign segfaults when
> >'File' is clicked on.
> >
> >Following Clive's hint I have found just 4 places XStoreName is used:
> >
> >lib/canvas.c:            XStoreName( flx->display, sp->window, ob->label );
> >lib/canvas.c:            XStoreName( flx->display, sp->window, name );
> >lib/popup.c:        XStoreName( flx->display, popup->win, popup->title );
> >lib/xpopup.c:        XStoreName( flx->display, m->win, m->title );
> >
> >but I do not have any idea how to fix the problem. I have even
> >localized the segfault to be originating in 'xpopup.c', with m->title
> >being 0x0, so I made it point to an empty static string (""). The
> >program did not segfault on "File" but aborted on "SaveAs" from File
> >popup, saying
> >munmap_chunk(): invalid pointer
> >Abort (core dumped)
> >
> >so I surrendered.
> >
> >Any more hints? Without working fdesign the whole library is pretty unusable 
> >:(
> >
> >regards, Michal
> >
> >On Wed, Jun 30, 2021 at 02:27:35AM +0100, Clive Stubbings wrote:
> >>
> >>Hi,
> >>
> >>There has been a regression in the xorg libX11
> >>
> >>It is likely this is your issue - it was spotted in one of my xforms 
> >>programs a few weeks ago by one of my users.
> >>
> >>XStoreName used to tolerate a NULL pointer (it checked before using it). 
> >>New code has been added ahead of that check.
> >>
> >>If your system has recently updated its libraries, thats likely the cause.
> >>
> >>I believe it has now been fixed upstream thanks to the person who spotted 
> >>the problem feeding the cause back to the developers and a new version 
> >>should come through in due course.
> >>
> >>If you need a quicker fix, hack the library to make sure it doesn't pass a 
> >>NULL pointer to XStoreName.
> >>
> >>Cheers
> >>Clive
> >>
> >>
> >>
> >>On Sun, 27 Jun 2021, ternaryd wrote:
> >>
> >>>On Sat, 26 Jun 2021 15:47:12 -0700
> >>>Coby Hochstein <cjh39@cox.net> wrote:
> >>>
> >>>>Hello,
> >>>>
> >>>>when I load fdesign and click on the "File"
> >>>>menu bar fdesign segmentation faults.
> >>>>I'm running xforms-1.2.4
> >>>>
> >>>>(gdb) run
> >>>>Starting program: /usr/local/bin/fdesign
> >>>>[Thread debugging using libthread_db enabled]
> >>>>Using host libthread_db library
> >>>>"/lib/arm-linux-gnueabihf/libthread_db.so.1".
> >>>>
> >>>>Program received signal SIGSEGV, Segmentation
> >>>>fault.
> >>>>strlen () at ../sysdeps/arm/armv6/strlen.S:26
> >>>>26 ../sysdeps/arm/armv6/strlen.S: No such
> >>>>file or directory.
> >>>>(gdb)
> >>>
> >>>
> >>>>Any idea ?
> >>>
> >>>fdesign is calculating the string length of a
> >>>string pointing to NULL.
> >>>
> >>>Use a version of fdesign compiled with debugging
> >>>enabled, run it again until crash, and check the
> >>>coredump in gdb. Use the "up" command until you
> >>>reach a stack level belonging to fdesign (or
> >>>xforms). You should see which pointer is NULL.
> >>>Then you can try to figure out, why it is NULL
> >>>and how to fix it.
> >>>
> >>>  $ ulimit -c unlimited
> >>>  $ ./fdesign ...
> >>>  $ gdb ./fdesign coredump
> >>>  (gdb> up
> >>>  ...
> >>>
> >>>you can query the value of any variable at the
> >>>time of the crash with
> >>>
> >>>  (gdb) p varname
> >>>
> >>>HTH
> >>>
> >>>--
> >>>Cris
> >>>
> >
> >-- 
> > Michal Szymanski (msz at astrouw dot edu dot pl)
> > Warsaw University Observatory, Warszawa, POLAND
> >

-- 
  Michal Szymanski (msz at astrouw dot edu dot pl)
  Warsaw University Observatory, Warszawa, POLAND