[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Bug#365381: marked as done (xdm fails to start user session after login, and restarts immediately)

Your message dated Sat, 26 May 2007 14:15:11 +0200
with message-id <465824CF.7040605@ens-lyon.org>
and subject line Bug#356858: xdm chokes on null pointers in address structures returned by getifaddrs()
has caused the attached Bug report to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what I am
talking about this indicates a serious mail system misconfiguration
somewhere.  Please contact me immediately.)

Debian bug tracking system administrator
(administrator, Debian Bugs database)
--- Begin Message --- 
Package: xdm
Version: 1:1.0.1-6
Severity: important

Hello,

After upgrading to Xorg 7.0 on two of my boxes (running Debian
unstable), I am unable to log into X using xdm. As soon as I enter
my login / password in the xdm dialog box, the X server is reset and
xdm restarts.

After doing some tests I think the problem is related to the 'unusual'
network interfaces I have on my machine -- I'm using OpenVPN on my boxes
and it creates 'tun' virtual network interfaces, that are not 'real'
ethernet interfaces.

By looking at the xdm source code, it seems that xdm forks a child
process after successful user authentication, in order to handle the
user X session. That child process starts by writing some .Xauthority
files in the user home directory, containing the list of IP addresses of
all the local network interfaces (DefineSelf() function in xdm/auth.c).

When I have OpenVPN running, the xdm child process crashes when
iterating over the list of my network interfaces IP addresses. It seems
that the DefineSelf() function calls the ConvertAddr() function with a
NULL saddr argument. A SIGSEGV signal is therefore sent to the xdm child
process, and xdm restarts immediately.

It is possible to prevent the problem by switching to false the
DisplayManager*authorize option in the /etc/X11/xdm/xdm-config file,
but I don't think that is very secure.

I'm running a 2.6.16 kernel I compiled myself. I think the problem may
be reproduced simply by running OpenVPN before authenticating in xdm.

Regards,

Yann Grossel

-- System Information:
Debian Release: testing/unstable
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'testing'), (500, 'stable')
Architecture: i386 (i686)
Shell:  /bin/sh linked to /bin/bash
Kernel: Linux 2.6.16.1
Locale: LANG=C, LC_CTYPE=C (charmap=ISO-8859-15) (ignored: LC_ALL set to en_GB.ISO-8859-15)

Versions of packages xdm depends on:
ii  cpp                          4:4.0.3-3   The GNU C preprocessor (cpp)
ii  debconf [debconf-2.0]        1.5.0       Debian configuration management sy
ii  libc6                        2.3.6-7     GNU C Library: Shared libraries
ii  libice6                      1:1.0.0-3   X11 Inter-Client Exchange library
ii  libpam0g                     0.79-3.1    Pluggable Authentication Modules l
ii  libselinux1                  1.30-1      SELinux shared libraries
ii  libsm6                       1:1.0.0-4   X11 Session Management library
ii  libx11-6                     2:1.0.0-6   X11 client-side library
ii  libxau6                      1:1.0.0-3   X11 authorisation library
ii  libxaw7                      1:1.0.1-5   X11 Athena Widget library
ii  libxdmcp6                    1:1.0.0-4   X11 Display Manager Control Protoc
ii  libxext6                     1:1.0.0-4   X11 miscellaneous extension librar
ii  libxinerama1                 1:1.0.1-4   X11 Xinerama extension library
ii  libxmu6                      1:1.0.1-3   X11 miscellaneous utility library
ii  libxpm4                      1:3.5.4.2-3 X11 pixmap library
ii  libxt6                       1:1.0.0-4   X11 toolkit intrinsics library
ii  x11-common                   1:7.0.15    X Window System (X.Org) infrastruc
ii  xbase-clients                1:7.0.0-5   miscellaneous X clients

xdm recommends no packages.

-- debconf information excluded

--- End Message ---
--- Begin Message --- 
Version: 1:1.0.4-1

Closing since the problem disappeared according to the submitter of #356858.

Brice

--- End Message ---
Reply to: