[Python-Dev] FWD: Python execvpe symlink race condition.

[Guido van Rossum]

[Aahz, quoting an anonymous security report]
> >> >> It is possible, to create a link of the file to be executed
> >> >> (t) in the limited time window between the statements
> >> >> os.path.exists(file) in tempfile.py and execv(t, ('blah',)) in
> >> >> os.py are executed.

[Zack]
> >> That is exactly the signature of one of the tempfile bugs that I
> >> fixed.  I do not know whether any official 2.2.x release has yet
> >> occurred that includes the bugfix.

[Aahz]
> > That's what I suspected.  Did you check that into the 2.2.x maint
> > branch?  (I remember that you did, but I'm triple-checking.)

[Zack]
> I don't have write privileges.  I thought that it was checked into the
> 2.2.x maint branch but I don't actually know.

Zack's changes to tempfile.py were *not* checked into Python 2.2 --
they require API changes that are difficult to justify.  (The changes
by Zack that you remember being checked into 2.2 were execve.)

A problem with Zack's tempfile changes is that many uses of mktemp are
perfectly safe, and the warning is so annoying that I decided to
disable the warning.

I'm not quite sure what to do now.

--Guido van Rossum (home page: http://www.python.org/~guido/)