From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 06 Dec 2011 15:06:12 GMT
Subject: Re: [PATCH] Set hard limit on delta chain depth
Message-ID: <7vvcpthh97.fsf@alter.siamese.dyndns.org>
In-Reply-To: <1323068688-31481-1-git-send-email-pclouds@gmail.com>

Nguyễn Thái Ngọc Duy  <pclouds@gmail.com> writes:

> Too deep delta chains can cause stack overflow in get_base_data(). Set
> a hard limit so that index-pack does not run out of stack. Also stop
> people from producing such a long delta chains using "pack-object
> --depth=<too large>"
>
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---
>  I used to make very long delta chains and triggered this in index-pack.
>  I did not care reporting because it's my fault anyway. Think again,
>  index-pack is called at server side and a malicious client can
>  trigger this. This patch does not improve the situation much, but at
>  least we won't get sigsegv at server side.

Why should we treat this condition any differently from the case where the
sender of a pack used beefier machine than you have and stuffed a huge
object that the index-pack running on your box cannot hold in core,
causing xmalloc() to die on your machine?

I do not think this is the right way to handle the issue. Your other patch
to flatten the recursion to iteration looked a lot saner approach.