On Thu, Feb 22, 2018 at 06:05:15PM -0500, Jeff King wrote:

On Thu, Feb 22, 2018 at 02:42:35PM -0800, Jonathan Nieder wrote:

quoted

quoted

I couldn't quite get it to work, but I think it's because I'm doing
something wrong with the submodules. But I also think this attack would
_have_ to be done over ssh, because on a local system the submodule
clone would a hard-link rather than a real fetch.

What happens if the submodule URL starts with file://?

Ah, that would do it. Or I guess any follow-up fetch.

I'm still having trouble convincing submodules to fetch _just_ the
desired sha1, though. It always just fetches everything. I know there's
a way that this kicks in (that's why we have things like
allowReachableSHA1InWant), but I'm not sufficiently well-versed in
submodules to know how to trigger it.

<facepalm> This won't work anyway. I was right when I said that we don't
redirect stderr for rev-list, but of course it's stdout that determines
the pager behavior. So I don't think you could get rev-list to trigger a
pager here.

I don't think there's currently any vulnerability, but it's more to do
with luck than any amount of carefulness on our part.

-Peff