From: Martin Koegler <mkoegler@auto.tuwien.ac.at>
Date: Fri, 14 Aug 2009 07:19:49 GMT
Subject: Re: [PATCH] Fix "unpack-objects --strict"
Message-ID: <20090814071949.GA2342@auto.tuwien.ac.at>
In-Reply-To: <7vocqiucpw.fsf@alter.siamese.dyndns.org>

On Thu, Aug 13, 2009 at 11:32:59PM -0700, Junio C Hamano wrote:
> Martin Koegler <mkoegler@auto.tuwien.ac.at> writes:
> > To introduce a object with one of its linked objects missing, left it
> > out of the pack and push it into the repository. unpack-objects will
> > unpack all objects and fail updating the ref (but leave all objects in
> > the repository). As second step, simply send a ref update request,
> > which should succed, as the object is present in the repository.
> 
> Your "ref update request" exploit does not work because your understanding
> of how we decide to allow updating a ref is flawed.
> 
> We do not blindly update a ref to a commit only because we happen to have
> that commit.  We require that commit to reach existing tips of refs
> without break.  The logic is in quickfetch() in builtin-fetch.c.

I'm talking on the server side of a push operation (receive-pack), not
the client side. The patchset should prevent invalid data from
entering the repository, thereby preventing upload-pack (during further
fetch operation) and other git programs (eg. called from gitweb) from
failing/segfaulting.

mfg Martin Kögler