From: Damien Robert <damien.olivier.robert@gmail.com>
Date: Thu, 12 Mar 2020 18:24:46 GMT
Subject: Re: [PATCH v2 1/1] midx.c: fix an integer overflow
Message-ID: <20200312182446.6zqjtudkptsvr6uh@feanor>
In-Reply-To: <20200312173520.2401776-1-damien.olivier.robert+git@gmail.com>

From Damien Robert, Thu 12 Mar 2020 at 18:35:20 (+0100) :
> When verifying a midx index with 0 objects, the
>     m->num_objects - 1
> overflows to 4294967295.
> 
> Fix this both by checking that the midx contains at least one oid,
> and also that we don't write any midx when there is no packfiles.

I forgot to add: previously I was wondering about a warning when in 'write'
when we only index one pack file, but this could make sense in the case of
a 'midx repack'. So I only warn if there is no objects.