From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 11 Jun 2024 17:03:10 GMT
Subject: Re: [PATCH v2 2/3] pack-bitmap.c: avoid uninitialized `pack_int_id` during reuse
Message-ID: <xmqqy17bwgxd.fsf@gitster.g>
In-Reply-To: <20240611091102.GL3248245@coredump.intra.peff.net>

Jeff King <peff@peff.net> writes:

> On Mon, Jun 10, 2024 at 04:10:53PM -0400, Taylor Blau wrote:
>
>> Avoid the uninitialized read by ensuring that the pack_int_id field is
>> set in the single-pack reuse case by setting it to either the MIDX
>> preferred pack's pack_int_id, or '0', in the case of single-pack
>> bitmaps.  In the latter case, we never read the pack_int_id field, so
>> the choice of '0' is arbitrary.
>
> Could we set it to some sentinel value for the single-pack case? If we
> set it to "-1", then the BUG() added in patch 3 would trigger if we did
> accidentally try to feed it to the midx code. Assuming you do not have
> 2^32-1 packs, of course. ;)

Yeah, I had exactly the same reaction.