Re: [PATCH] fsckObjects tests: show how v2.17.1 can exploit downstream

[Jeff King <peff@peff.net>]

On Wed, May 30, 2018 at 10:32:19AM +0900, Junio C Hamano wrote:

> If we want to also encourage people to vet their own "fetches", I am
> not against extending documentation.  It just is different from "we
> extended the mechanism to help server side protect their clients"
> that was the focus of (updated, relative to what is in the tarball)
> the description in the release notes.

I haven't tested it, but I suspect that doing multiple fetches could
result in passing bad objects through a fetch.fsckObjects filter.
Because the objects aren't quarantined on fetch, and because
fsck_finish() requires the objects to be installed into place, they may
still exist in the repository even if we end up rejecting them. Would a
subsequent fetch hit the quickfetch() code and update without actually
sending the objects again?

This problem is specific to the .gitmodules thing, I think, because the
other fsck checks are able to die much earlier (before fsck_finish).

I think in the long run fetch should implement a similar quarantine
procedure to what happens on push.

-Peff