Bug#956454: gmsh: Gmsh segfaults at startup

[Thomas V.]

Package: gmsh
Version: 4.6.0+ds1-1
Followup-For: Bug #956454

Dear Maintainer,

Gmsh segfaults at startup, even for systems without the radeon driver (I am
using nouveau). Here is a transcript:

$ gmsh
Segmentation fault

Running gdb reports the error in:
Thread 1 "gmsh" received signal SIGSEGV, Segmentation fault.
0x00007ffff66e516e in XFillRectangle () from /usr/lib/x86_64-linux-gnu/libX11.so.6

and the backtrace is:
#0  0x00007ffff66e516e in XFillRectangle () from /usr/lib/x86_64-linux-gnu/libX11.so.6
#1  0x00007ffff68bed9a in Fl_Graphics_Driver::rectf(int, int, int, int) () from /usr/lib/x86_64-linux-gnu/libfltk.so.1.3
#2  0x00007ffff7612a05 in drawContextFltkStringTexture::queueString::flush() () from /usr/lib/x86_64-linux-gnu/libgmsh.so.4.6
#3  0x00007ffff75f4092 in openglWindow::draw() () from /usr/lib/x86_64-linux-gnu/libgmsh.so.4.6
#4  0x00007ffff69439f5 in Fl_Gl_Window::flush() () from /usr/lib/x86_64-linux-gnu/libfltk_gl.so.1.3
#5  0x00007ffff6848117 in Fl::flush() () from /usr/lib/x86_64-linux-gnu/libfltk.so.1.3
#6  0x00007ffff6849170 in Fl::wait(double) () from /usr/lib/x86_64-linux-gnu/libfltk.so.1.3
#7  0x00007ffff684924d in Fl::check() () from /usr/lib/x86_64-linux-gnu/libfltk.so.1.3
#8  0x00007ffff6f4d988 in Msg::Direct(char const*, ...) () from /usr/lib/x86_64-linux-gnu/libgmsh.so.4.6
#9  0x00007ffff75c428d in FlGui::instance(int, char**, bool, void (*)(char const*, ...)) () from /usr/lib/x86_64-linux-gnu/libgmsh.so.4.6
#10 0x00007ffff6f3c8d8 in GmshFLTK(int, char**) () from /usr/lib/x86_64-linux-gnu/libgmsh.so.4.6
#11 0x00007ffff6f3dafb in GmshMainFLTK(int, char**) () from /usr/lib/x86_64-linux-gnu/libgmsh.so.4.6
#12 0x00007ffff6990cca in __libc_start_main (main=0x555555555050 <main>, argc=1, argv=0x7fffffffde88, init=<optimized out>, 
    fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffde78) at ../csu/libc-start.c:308
#13 0x000055555555508a in _start ()

Best Regards,
Thomas

-- System Information:
Debian Release: bullseye/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.9.0-1-amd64 (SMP w/8 CPU threads)
Kernel taint flags: TAINT_FIRMWARE_WORKAROUND, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8), LANGUAGE=en_US:en
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages gmsh depends on:
ii  libc6     2.31-4
ii  libgmsh4  4.6.0+ds1-1

Versions of packages gmsh recommends:
ii  gmsh-doc  4.6.0+ds1-1

gmsh suggests no packages.

-- no debconf information