Re: Memory corruption when rebasing with git version 1.8.1.5 on arch

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 19, 2013, 16:02 UTC
Message-ID: <7vobefjs26.fsf@alter.siamese.dyndns.org>
In-Reply-To: <20130319134452.GA6752@sigill.intra.peff.net>

Jeff King <peff@peff.net> writes:

Show 6 quoted lines

> and so on. I haven't quite figured out what is going on. It looks like
> we call update_pre_post_images with postlen==0, which causes it to just
> write the fixed postimage into the existing buffer. But of course the
> fixed version is bigger, because we are expanding the tabs into 8
> spaces (but it _doesn't_ break if each line starts with only one tab,
> which confuses me).

I used to be intimately familiar with the update_pre_post_images() function, but the version after 86c91f91794c (git apply: option to ignore whitespace differences, 2009-08-04), I won't vouch for it doing anything sensible. We recently had to do 5de7166d46d2 (apply.c:update_pre_post_images(): the preimage can be truncated, 2012-10-12) to fix one of its corner cases but I would not be surprised if there are other cases the function gets it all wrong.

I'd come back to the topic after I finish other tasks on my plate, so if somebody is inclined please go ahead digging this a bit further; I won't have much head start to begin with in this code X-<.