Python buffer overflow

A bug was found in the way python determines the realpath() of the
current script.  The realpath() function is broken by design and
should not be used.

http://www.gotfault.net/research/exploit/gexp-python.py
http://www.gotfault.net/research/advisory/gadv-python.txt

I can crash FC4 and RHEL4 with this exploit.  Need to look at the
source.  It should have a low impact as you have to run a python
program from within a direcotory which is part of an insanely long
path.  The other distributions are likely not crashing as the maximum
path length returned by realpath() can differ.

Further testing has shown that this issue ONLY affects a python
program which resides inside the very long path (realpath, so you
can't use symlinks to fake it, a hardlink will work though).  Simply
running a python program with your CWD very long does nothing.

We don't allow suid python scripts, which means the only real path of
exploitation would be to trick another user into doing something
silly.  consolehelper adds quite a lot of sanity to how we run python
programs as root.



This issue also affects FC4