Re: [PATCH] cherry: cache patch-ids to avoid repeating work

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Jul 10, 2008, 14:28 UTC
Message-ID: <alpine.DEB.1.00.0807101526380.18205@racer>
In-Reply-To: <7f9d599f0807100709u778f0ab1y28776d7efb831b61@mail.gmail.com>

Hi,

On Thu, 10 Jul 2008, Geoffrey Irving wrote:

Show 14 quoted lines

> On Wed, Jul 9, 2008 at 8:34 PM, Geoffrey Irving <irving@naml.us> wrote:
>
> > Note: there are at least two "holes" in this code.  First, it is 
> > impossible to verify the validity of the entries (this is impossible 
> > to fix).  Second, it is possible to write a malicious patch-id-cache 
> > file that causes git-cherry to go into an infinite loop.  Fixing the 
> > loop requires either traversing every entry on load (bad) or adding a 
> > second loop termination condition to find_helper.  Since looping 
> > forever is better than returning incorrect results, I figured fixing 
> > the weaker hole would just result in a false sense of security.
> 
> Oops: avoiding the infinite loop only requires reading expected O(1) 
> entries on load, so I can fix that if you like.  It would only be all of 
> them if it actually did detect the infinite loop.

I have to admit that you lost me there. AFAIR the patch-id cache is a simple commit->patch_id store, right? Then there should be no way to get an infinite loop.

Besides, this is a purely local cache, no? Never to be transmitted... So not much chance of a malicious attack, except if you allow write access to your local repository, in which case you are endangered no matter what.

Ciao, Dscho