X server crashes when changing font size in LibreOffice / 'Failed to compile FS'

[Stefan Pietsch <stefan+debian@shellforce.org>]

Dear list,

when enlarging text in LibreOffice Writer (e.g. 96pt) so that the characters fill the screen, the X server reproducibly crashes.
I'm running Debian sid with the package xorg-server
 21.1.7-1. Hardware is a ThinkPad T410 with integrated Intel graphics.



Xorg.0.log:
###########


[   331.177] Failed to compile FS: 0:1(10): error: GLSL 1.30 is not supported. Supported versions are: 1.10, 1.20, and 1.00 ES



[   331.177] Program source:

#version 130

#ifdef GL_ES

precision mediump float;

#endif

#define RepeatNone                            0

#define RepeatNormal                     1

#define RepeatPad                        2

#define RepeatReflect                    3

#define RepeatFix                             10

uniform int                     source_repeat_mode;

uniform int                     mask_repeat_mode;

vec2 rel_tex_coord(vec2 texture, vec4 wh, int repeat)

{

        vec2 rel_tex;

        rel_tex = texture * wh.xy;

        if (repeat == RepeatFix + RepeatNone)

                return rel_tex;

        else if (repeat == RepeatFix + RepeatNormal)

                rel_tex = floor(rel_tex) + (fract(rel_tex) / wh.xy);

        else if (repeat == RepeatFix + RepeatPad) {

                if (rel_tex.x >= 1.0)

                        rel_tex.x = 1.0 - wh.z * wh.x / 2.;

                else if (rel_tex.x < 0.0)

                        rel_tex.x = 0.0;

                if (rel_tex.y >= 1.0)

                        rel_tex.y = 1.0 - wh.w * wh.y / 2.;

                else if (rel_tex.y < 0.0)

                        rel_tex.y = 0.0;

                rel_tex = rel_tex / wh.xy;

        } else if (repeat == RepeatFix + RepeatReflect) {

                if ((1.0 - mod(abs(floor(rel_tex.x)), 2.0)) < 0.001)

[   331.177] (EE)

Fatal server error:

[   331.177] (EE) GLSL compile failure

[   331.177] (EE)

[   331.177] (EE)

Please consult the The X.Org Foundation support

         at http://wiki.x.org

 for help.

[   331.177] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.

[   331.177] (EE)

[   331.177] (II) AIGLX: Suspending AIGLX clients for VT switch

[   331.243] (EE) Server terminated with error (1). Closing log file.



####################


Disabling "glamor" with a configuration file in /etc/X11/xorg.conf.d/ solves this and the X server does not crash:


#####

Section "Device"

	Identifier ""

	Driver "modesetting"

	Option "Accelmethod" "none"

EndSection



Section "Module"

	Disable "glamoregl"

EndSection


#####



If anybody is experiencing the same issue, this is the upstream bug: https://gitlab.freedesktop.org/xorg/xserver/-/issues/1336
A fix has been merged recently: https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1066

I have not been able to test it yet.


Regards,
Stefan