Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Date: Sat, 5 Nov 2011 14:35:08 +0400
From: Solar Designer <>
Subject: Re: CVE request: unsafe use of /tmp in multiple CPAN modules

On Fri, Nov 04, 2011 at 01:14:46PM -0500, John Lightsey wrote:
> On 11/04/2011 11:36 AM, Solar Designer wrote:
> > On Fri, Nov 04, 2011 at 09:46:45AM -0500, John Lightsey wrote:
> >> PAR::Packer - PAR packed files are extracted to unsafe and predictable
> >> temporary directories
> >>
> >>
> > 
> > I think that your description for this one happens to encourage a poor
> > fix for it.  Specifically, starting the description by "par_mktmpdir()
> > makes no effort to verify that the /tmp/par-<username> directory is safe
> > to use" may result in this function being patched to do such checks,
> > which I think would be a poor fix.  A better fix would be to properly
> > create a temporary files directory, with a less predictable name and
> > with due retries (with new names) if the directory already exists -
> > preferably using File::Temp's tempdir().
> The problem with using random directory names here is that the
> /tmp/par-user directory is being used as a caching mechanism to avoid
> extracting the PAR contents over and over.

Oh, I did not realize that.

> A better alternative may be
> to use $ENV{'HOME'}/.par or something along those lines.

Makes sense to me.  Use of env vars is unsafe in a potentially SUID
script, but I don't know what the current policy regarding this is in
CPAN.  Are CPAN modules by default supposed to be safe for use in SUID
Perl scripts or not - I guess not, or we'd have plenty of CVE ids for
those issues by now?  An alternative would be to find the home
directory path from the real UID.


Powered by blists - more mailing lists

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.