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Security update for gdm2

Knowledgebase

(Last modified: 18AUG2003)


solutions Security update for gdm2 SuSE Linux Maintenance Web (3aa6844b8b167793ea311c09bf8d62f0)

Applies to

Product(s): SuSE Linux Enterprise Server 8 for x86
SuSE Linux Enterprise Server 8 for IBM iSeries and IBM pSeries
SuSE Linux Enterprise Server 8 for IBM S/390 and IBM zSeries
SuSE Linux Enterprise Server 8 for IBM zSeries
SuSE Linux Openexchange Server 4
SuSE Linux Enterprise Server 8 for IPF
SuSE Linux Enterprise Server 8 for AMD64
SuSE Linux Desktop 1.0

Package: gdm2
Release: 20030818
Obsoletes: none

Indications

This update should be installed if GDM is installed.

Problem description

Code written to originally run as the user who was logged in is being run as root. This is the code that allows examining the ~/.xsession-errors file. Originally this was supposed to run as the user and thus there was no real security for the read code. Unfortunately due to the way it was developed it was run as root for different reasons and the read code was never retrofitted to be safe. Thus if the user just makes a symlink from ~/.xsession-errors to any file on the system during the session, and makes sure the session lasts less then 10 seconds, then the user can examine the file as long as it was readable as a text file. This patch disabled the reading of the .xsession-errors file.
The next problem is caused by a missing "continue" statement in a loop, which leads to a structure being used right after being freed from memory. This situation can happen if the chosen host is not responding while the client keeps trying new indirect queries. This patch adds the missing "continue" statement.
Another problem was caused by not checking the length of the authorization data string first, before checking it with strncmp. If the data is less then 18 bytes long then the daemon may wander off the end of the string a few bytes in the strncmp perhaps causing a SEGV. This patch adds a check for the length of the string before checking it with strncmp.

Solution

Please install the updates provided at the location noted below.

Installation notes

This update is provided as an RPM package that can easily be installed onto a running system by using this command:
rpm -Uvh gdm2.rpm

links to download packages

Download Source Packages

Download the source code of the patches for maintained products.


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