Bug#1130867: xvfb: Reproducible segfault on s390x when running PyQt6 app testsuite

Package: xvfb
Version: 2:21.1.21-1
Severity: normal
X-Debbugs-Cc: [email protected], [email protected]
User: [email protected]
Usertags: s390x

Hi,

While debugging autopkgtest failures on the napari-console package,
I found out that on s390x they're caused by a reproducible crash in
xvfb.

To reproduce, checkout commit 5e2bdc336376807589c2aef22f3a50229a8ca9b4
of [email protected]:python-team/packages/napari-console, remove the
test for s390x in debian/tests/control, and run autopkgtest. You'll find
*.log files for both xvfb and the window manager.

In my case, the xvfb log looked like the following:

(EE)
(EE) Backtrace:
(EE) 0: /usr/bin/Xvfb (xorg_backtrace+0x5a) [0x2aa1a9ad402]
(EE) 1: /usr/bin/Xvfb (0x2aa1a800000+0x1b18ea) [0x2aa1a9b18ea]
(EE) 2: linux-vdso64.so.1 (__kernel_rt_sigreturn+0x0) [0x3ffd84fe4e0]
(EE) 3: /usr/bin/Xvfb (CreatePicture+0x9e) [0x2aa1a8d1df6]
(EE) 4: /usr/bin/Xvfb (0x2aa1a800000+0x138634) [0x2aa1a938634]
(EE) 5: /usr/bin/Xvfb (0x2aa1a800000+0x139852) [0x2aa1a939852]
(EE) 6: /usr/bin/Xvfb (0x2aa1a800000+0x13779c) [0x2aa1a93779c]
(EE) 7: /usr/bin/Xvfb (0x2aa1a800000+0x180a8a) [0x2aa1a980a8a]
(EE) 8: /usr/bin/Xvfb (MapWindow+0x130) [0x2aa1a9838d8]
(EE) 9: /usr/bin/Xvfb (0x2aa1a800000+0x1491e8) [0x2aa1a9491e8]
(EE) 10: /usr/bin/Xvfb (0x2aa1a800000+0x14ff68) [0x2aa1a94ff68]
(EE) 11: /usr/bin/Xvfb (0x2aa1a800000+0x154aca) [0x2aa1a954aca]
(EE) 12: /usr/lib/s390x-linux-gnu/libc.so.6 (0x3ffa7700000+0x2ccba) [0x3ffa772ccba]
(EE) 13: /usr/lib/s390x-linux-gnu/libc.so.6 (__libc_start_main+0xa8) [0x3ffa772cdb0]
(EE) 14: /usr/bin/Xvfb (0x2aa1a800000+0x445b8) [0x2aa1a8445b8]
(EE)
(EE) Segmentation fault at address 0x0
(EE)
Fatal server error:
(EE) Caught signal 11 (Segmentation fault). Server aborting
(EE)

I'm disabling the tests on that architecture for now since I have no
idea how to proceed, but I'll gladly help test any suggested fix :-)

Roland.
-- System Information:
Debian Release: forky/sid
  APT prefers unstable-debug
  APT policy: (500, 'unstable-debug'), (500, 'unstable')
Architecture: s390x

Kernel: Linux 6.12.74+deb13+1-s390x (SMP w/2 CPU threads)
Locale: LANG=C, LC_CTYPE=C.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: unable to detect

Versions of packages xvfb depends on:
ii  libaudit1       1:4.1.2-1+b1
ii  libc6           2.42-13
ii  libgl1          1.7.0-3
ii  libnettle8t64   3.10.2-1
ii  libpixman-1-0   0.46.4-1+b1
ii  libselinux1     3.9-4+b1
ii  libsystemd0     260~rc4-1
ii  libxau6         1:1.0.11-1+b1
ii  libxdmcp6       1:1.1.5-2
ii  libxfont2       1:2.0.6-2
ii  xserver-common  2:21.1.21-1

Versions of packages xvfb recommends:
pn  xauth  <none>

xvfb suggests no packages.

-- no debconf information