Bug#495797: an xdmcp enabled gdm crashes if an Xwilling script runs
Utku Somer
utku at parkyeri.com
Wed Aug 20 13:46:06 UTC 2008
Package: gdm
Version: 2.20.7-1
Severity: normal
*** Please type your report below this line ***
gdm seems to crash when I put a Xwilling script in my /etc/gdm/
directory (or alternatively when I tell it to execute a script
elsewhere with my gdm.conf.) When an XDMCP query hits the server, I
see this line in /var/log/syslog, which indicates a crash:
Aug 19 23:31:59 beazley gdm[13615]: WARNING: main daemon: Got SIGABRT.
Something went very wrong. Going down!
The server shows up on an xdmcp chooser on the first query (which
crashes it), but the latter queries show up with nothing. gdm prints
the crash message once, but the gdm process goes on, not honoring the
further XDMCP queries.
My setup is running the xmdcp enabled gdm on a vserver, so I can no
longer login to this machine over gdm with this setup. I have
reproduced the bug on a friend's laptop as well, the result is the
same as above, gdm stops honoring XDMCP queries, but it keeps running
and does not completely crash, and it still lets local logins.
And another funny thing. When I enable debug in my gdm.conf, I DON'T
see the crash message, but regular lines which don't indicate the
crash has happened. But the result is the same. Here are the lines:
Aug 20 15:57:00 beazley gdm[12087]: DEBUG: mainloop_sig_callback: Got
signal 17
Aug 20 15:57:00 beazley gdm[12087]: DEBUG: decode_packet: GIOCondition 1
Aug 20 15:57:00 beazley gdm[12087]: DEBUG: XDMCP: Received opcode
BROADCAST_QUERY from client 192.168.199.70 : 33177
Aug 20 15:57:00 beazley gdm[12087]: DEBUG: gdm_xdmcp_host_allow:
client->hostname is 192.168.199.70
Aug 20 15:57:00 beazley gdm[12087]: DEBUG: XDMCP: Sending WILLING to
192.168.199.70
Aug 20 15:57:00 beazley gdm[12087]: DEBUG: mainloop_sig_callback: Got
signal 17
Aug 20 15:57:02 beazley gdm[12087]: DEBUG: decode_packet: GIOCondition 1
Aug 20 15:57:02 beazley gdm[12087]: DEBUG: XDMCP: Received opcode
BROADCAST_QUERY from client 192.168.199.70 : 33177
Aug 20 15:57:02 beazley gdm[12087]: DEBUG: gdm_xdmcp_host_allow:
client->hostname is 192.168.199.70
Aug 20 15:57:02 beazley gdm[12087]: DEBUG: XDMCP: Sending WILLING to
192.168.199.70
Note that no further messages can be seen for gdm in syslog after
this. For example, `/etc/init.d/gsm stop` command will produce no
output in syslog (which it would if there was no crash.)
Workaround:
===========
My workaround is disabling Xwilling messages for now, by removing them
from /etc/gdm directory and disabling the lines in gdm.conf.
Files & Outputs:
================
Here is my gdm.conf, without debug:
-------------------------------------------
######gdm.conf starts######
# Have fun!
[daemon]
[security]
#Willing=/etc/gdm/Xwilling
[xdmcp]
Enable=True
HonorIndirect=True
[gui]
[greeter]
[chooser]
[debug]
[servers]
0=inactive
######gdm.conf ends######
Here are the innards of my /etc/gdm/Xwilling script:
----------------------------------------------------
#!/bin/bash
echo "Be like water."
-- System Information:
Debian Release: lenny/sid
APT prefers testing
APT policy: (500, 'testing'), (500, 'stable')
Architecture: i386 (i686)
Kernel: Linux 2.6.22-pybigvserver (SMP w/4 CPU cores)
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)
Shell: /bin/sh linked to /bin/bash
Versions of packages gdm depends on:
ii adduser 3.108 add and remove users and groups
ii debconf [debconf-2.0] 1.5.22 Debian configuration
management sy
ii gksu 2.0.0-5 graphical frontend to su
ii gnome-session [x-sessi 2.22.3-1 The GNOME 2 Session Manager
ii gnome-terminal [x-term 2.22.3-2 The GNOME 2 terminal
emulator appl
ii libart-2.0-2 2.3.20-2 Library of functions for 2D
graphi
ii libatk1.0-0 1.22.0-1 The ATK accessibility toolkit
ii libattr1 1:2.4.43-1 Extended attribute shared
library
ii libc6 2.7-13 GNU C Library: Shared libraries
ii libcairo2 1.6.4-6 The Cairo 2D vector
graphics libra
ii libdbus-1-3 1.2.1-2 simple interprocess
messaging syst
ii libdbus-glib-1-2 0.76-1 simple interprocess
messaging syst
ii libdmx1 1:1.0.2-3 X11 Distributed Multihead
extensio
ii libfontconfig1 2.6.0-1 generic font configuration
library
ii libfreetype6 2.3.7-1 FreeType 2 font engine,
shared lib
ii libglade2-0 1:2.6.2-1 library to load .glade
files at ru
ii libglib2.0-0 2.16.4-2 The GLib library of C routines
ii libgnomecanvas2-0 2.20.1.1-1 A powerful object-oriented
display
ii libgtk2.0-0 2.12.11-3 The GTK+ graphical user
interface
ii libpam-modules 0.99.7.1-7 Pluggable Authentication
Modules f
ii libpam-runtime 0.99.7.1-7 Runtime support for the PAM
librar
ii libpam0g 0.99.7.1-7 Pluggable Authentication
Modules l
ii libpango1.0-0 1.20.5-1 Layout and rendering of
internatio
ii librsvg2-2 2.22.2-2 SAX-based renderer library
for SVG
ii librsvg2-common 2.22.2-2 SAX-based renderer library
for SVG
ii libselinux1 2.0.65-2 SELinux shared libraries
ii libwrap0 7.6.q-15 Wietse Venema's TCP
wrappers libra
ii libx11-6 2:1.1.4-2 X11 client-side library
ii libxau6 1:1.0.3-3 X11 authorisation library
ii libxdmcp6 1:1.0.2-3 X11 Display Manager Control
Protoc
ii libxext6 2:1.0.4-1 X11 miscellaneous extension
librar
ii libxi6 2:1.1.3-1 X11 Input extension library
ii libxinerama1 2:1.0.3-2 X11 Xinerama extension library
ii libxml2 2.6.32.dfsg-2 GNOME XML library
ii lsb-base 3.2-12 Linux Standard Base 3.2
init scrip
ii metacity [x-window-man 1:2.22.0-1 A lightweight GTK2 based
Window Ma
ii zlib1g 1:1.2.3.3.dfsg-12 compression library - runtime
Versions of packages gdm recommends:
ii dialog 1.1-20080316-1 Displays user-friendly
dialog boxe
ii gdm-themes 0.6 Themes for the GNOME
Display Manag
ii whiptail 0.52.2-11.3 Displays user-friendly
dialog boxe
ii xserver-xephyr 2:1.4.2-3 nested X server
ii xserver-xorg 1:7.3+15 the X.Org X server
ii zenity 2.22.1-1 Display graphical dialog
boxes fro
Versions of packages gdm suggests:
ii libpam-gnome-keyring 2.22.3-1 PAM module to unlock the
GNOME key
ii locales 2.7-13 GNU C Library: National
Language (
ii uswsusp 0.7-1.2 tools to use userspace
software su
-- debconf information:
gdm/daemon_name: /usr/bin/gdm
* shared/default-x-display-manager: gdm
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