[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <mpro.n92ies014eut609mb.taviso@cmpxchg8b.com>
Date: Mon, 21 Jul 2014 08:16:05 -0700
From: Tavis Ormandy <taviso@...xchg8b.com>
To: oss-security@...ts.openwall.com
Subject: Re: Re: glibc locale issues
Florian Weimer <fweimer@...hat.com> wrote:
> On 07/14/2014 04:15 AM, Tavis Ormandy wrote:
> > Tavis Ormandy <taviso@...xchg8b.com> wrote:
> >
> > > I just remembered another charset issues I had looked into but
> > > abandoned.
> >>
> > > First of all, I think the need_so logic in gconv_trans is broken, but
> > > even if it worked there is an off by one error in
> > > __gconv_translit_find() (it does + 3 instead of + 3 + 1 in the
> > > allocation.
> >
> > To be clear, I suspect this is exploitable. It would be nice if you
> > could modify the buffer such that gconv will open a path with a string
> > you've appended it (e.g. CHARSET=//. pkexec ./../../../../tmp/foo.so),
>
> This is about the glib part and the alias processing, right?
No, it's nothing to do with glib.
>
> iconv/gconv_charset.h:strip() normalizes the transliteration argument to
> iconv_open, so the resulting file names follow a particular pattern, and
> there cannot be enough slashes to ascend to a writable directory.
Is it possible you're thinking of the LC_ALL thing? (the questionable
ForceCommand bypass with path traversal if you're forcecommand'd to an
application that does something odd with localized strings and you can
create a file and your sshd has been configured with AcceptEnv LC_*). This
is an unrelated heap overflow - not a path traversal.
>
> > if not maybe the one byte overflow is still exploitable.
>
> Hmm. How likely is that? It overflows in to malloc metadata, and the
> glibc malloc hardening should catch that these days.
>
No, it's quite definitely possible, I'm really close but was busy this week.
Tavis.
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.
