Subject: Re: [X2Go-Dev] Bug#1172: ThunderBird crashes in PubApp mode on amd64

From: Ulrich Sibiller <[email-masked]>
Date: Mon, 8 May 2017 00:07:45 +0200

On Fri, May 5, 2017 at 4:30 PM, Stefan Baur <[email-masked]> wrote:
> package: nx-libs
>
> Hi,
>
> since Debian Jessie (stable) switched from IceDove back to ThunderBird,
> TB crashes when the host is an amd64 machine and X2GoClient is running
> in PubApp mode. i386 is unaffected.
>
> It happens with X2GoClient on Windows as well as on Linux, so it's not a
> matter of VcXsrv being too old/broken/whatever.
>
> It also happens when all X2Go server components are installed from heuler.
>
> It does NOT happen when you build nx-libs from source using the Debian
> Experimental repository.
>
> So there's something in the stable nx-libs that's broken on amd64 only,
> and got fixed in the nx-libs version that is available via Debian
> Experimental.
>
> Core-Devs, please advise how to fix this - should we dare making a new
> nx-libs release and declare it stable, based on what is in Debian
> Experimental (arguing that everything is better than what we currently
> have)?  Or should we try to hunt down the offending code part and only
> patch that?  If the latter, who's willing to take a stab at it?  (We
> don't have a business case ATM, as all my TB-PubApp-users are still on
> i386, so no funding as of now.)

It is working for me with 3.5.99.7. So we already have fix.

The error message you posted is this:
traps: x2goagent [3339] general protection ip:7f02464e2e6d
sp:7ffef6c22150error:0 in libNX_X11.so.6.2[7f0246496000+123000]

So we have a problem in libNX_X11 which - in 3.5.9.77 - is on the
current xorg upstream level 1.6.5. In nx-libs 3.5.0.32 it is rather
old (about 1.3.3). I am curious if it is sufficient to ONLY copy
libNX_X11.so* from 3.5.99.7 to your crashing installation. If that
helps we could release 3.5.0.33 or 34 with that libX11 exchanged. This
should generally be bit much less risky than just marking 3.5.99 as
stable.

On the other hand: we have fixed lots of security and stability bugs
in 3.5.99.x so using those versions is generally advisable (from my
POV).

You could try to install libNX_X11-dbg and attach gdb to x2goagent
(run "gdb -p $(pidof x2goagent)") just before starting thunderbird.
When it crashes you'll get a backtrace. Using that information we can
(hopefully) see if a quick backport could help. That would be the
least invasive solution.

Comments?

Uli