From: Shawn O. Pearce <spearce@spearce.org>
Date: Wed, 14 Oct 2009 16:12:59 GMT
Subject: Re: git hang with corrupted .pack
Message-ID: <20091014161259.GK9261@spearce.org>
In-Reply-To: <alpine.LFD.2.00.0910141208170.20122@xanadu.home>

Nicolas Pitre <nico@fluxnic.net> wrote:
> > Some types of corruption to a pack may confuse the deflate stream
> > which stores an object.  In Andy's reported case a 36 byte region
> > of the pack was overwritten, leading to what appeared to be a valid
> > deflate stream that was trying to produce a result larger than our
> > allocated output buffer could accept.
...
> This is unfortunate that making a test case for this isn't exactly 
> trivial.

Hmmm.  We could do something like manually create a pack file of
one non-delta blob whose pack header length is 16, but use a zlib
stream whose result body is 64.  Prior to this fix, we'd be stuck
in the infinite loop.  :-)

Its a PITA to create though, you have to hand-craft the test vector
and save it in the repository, we can't produce such a pack with
any real code we ship.

-- 
Shawn.