Bug#1079683: gdm3: GDM3 receives SIGTRAP when gnome-session is not installed

[George Bartolomey]

Package: gdm3
Version: 43.0-3
Severity: important

Dear Maintainer,

I installed gdm3 package and started gdm3 service, but service seems to
received SIGTRAP signal. I checked all what I could and came to the
conclusion that gdm fails when no session files are available.
There was no log messages at all from gdm3 and other services related to
this bug.

Installation of gnome-session solves the issue.

I excepted that GDM starts when no session files available, but just say
to user that no DE installed.

Best regards,
George Bartolomey

-- System Information:
Debian Release: 12.6
   APT prefers stable-updates
   APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 
'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 6.1.0-23-amd64 (SMP w/12 CPU threads; PREEMPT)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), 
LANGUAGE=en_US:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages gdm3 depends on:
ii  accountsservice                    22.08.8-6
ii  adduser                            3.134
ii  dbus [default-dbus-system-bus]     1.14.10-1~deb12u1
ii  dbus-bin                           1.14.10-1~deb12u1
ii  dbus-daemon                        1.14.10-1~deb12u1
ii  dconf-cli                          0.40.0-4
ii  dconf-gsettings-backend            0.40.0-4
ii  debconf [debconf-2.0]              1.5.82
ii  gir1.2-gdm-1.0                     43.0-3
ii  gnome-session [x-session-manager]  43.0-1+deb12u1
ii  gnome-session-bin                  43.0-1+deb12u1
ii  gnome-session-common               43.0-1+deb12u1
ii  gnome-settings-daemon              43.0-4
ii  gnome-shell                        43.9-0+deb12u2
ii  gsettings-desktop-schemas          43.0-1
ii  libaccountsservice0                22.08.8-6
ii  libaudit1                          1:3.0.9-1
ii  libc6                              2.36-9+deb12u7
ii  libcanberra-gtk3-0                 0.30-10
ii  libcanberra0                       0.30-10
ii  libgdk-pixbuf-2.0-0                2.42.10+dfsg-1+deb12u1
ii  libgdm1                            43.0-3
ii  libglib2.0-0                       2.74.6-2+deb12u3
ii  libglib2.0-bin                     2.74.6-2+deb12u3
ii  libgtk-3-0                         3.24.38-2~deb12u1
ii  libgudev-1.0-0                     237-2
ii  libkeyutils1                       1.6.3-2
ii  libpam-modules                     1.5.2-6+deb12u1
ii  libpam-runtime                     1.5.2-6+deb12u1
ii  libpam-systemd [logind]            252.26-1~deb12u2
ii  libpam0g                           1.5.2-6+deb12u1
ii  librsvg2-common                    2.54.7+dfsg-1~deb12u1
ii  libselinux1                        3.4-1+b6
ii  libsystemd0                        252.26-1~deb12u2
ii  libx11-6                           2:1.8.4-2+deb12u2
ii  libxau6                            1:1.0.9-1
ii  libxcb1                            1.15-1
ii  libxdmcp6                          1:1.1.2-3
ii  polkitd                            122-3
ii  procps                             2:4.0.2-3
ii  systemd-sysv                       252.26-1~deb12u2
ii  ucf                                3.0043+nmu1
ii  x11-common                         1:7.7+23
ii  x11-xserver-utils                  7.7+9+b1
ii  xfwm4 [x-window-manager]           4.18.0-1
ii  xterm [x-terminal-emulator]        379-1

Versions of packages gdm3 recommends:
ii  at-spi2-core                       2.46.0-5
ii  desktop-base                       12.0.6+nmu1~deb12u1
ii  gnome-session [x-session-manager]  43.0-1+deb12u1
ii  x11-xkb-utils                      7.7+7
pn  xserver-xephyr                     <none>
ii  xserver-xorg                       1:7.7+23
pn  zenity                             <none>

Versions of packages gdm3 suggests:
pn  libpam-fprintd        <none>
pn  libpam-gnome-keyring  <none>
pn  libpam-pkcs11         <none>
pn  libpam-sss            <none>
pn  orca                  <none>

-- debconf information:
* shared/default-x-display-manager: gdm3
   gdm3/daemon_name: /usr/sbin/gdm3