Re: [PATCH 2/1] apply: reject input that touches outside $cwd

From: Jeff King <peff@peff.net>
Date: Jan 30, 2015, 18:24 UTC
Message-ID: <20150130182456.GA29477@peff.net>
In-Reply-To: <xmqqzj91cfnl.fsf_-_@gitster.dls.corp.google.com>

On Thu, Jan 29, 2015 at 03:48:14PM -0800, Junio C Hamano wrote:

Show 10 quoted lines

> By default, a patch that affects outside the working area is
> rejected as a mistake; Git itself never creates such a patch
> unless the user bends backwards and specifies nonstandard
> prefix to "git diff" and friends.
> 
> When `git apply` is used without either `--index` or `--cached`
> option as a "better GNU patch", the user can pass `--allow-uplevel`
> option to override this safety check.  This cannot be used to escape
> outside the working tree when using `--index` or `--cached` to apply
> the patch to the index.

It looks like your new --allow-uplevel goes to verify_path(). So this isn't just about "..", but it will also protect against applying a patch inside ".git". Which seems like a good thing to me, but I wonder if the option name is a little misleading. It is really about applying the same checks we do for index paths to the non-index mode of "git apply".

>  * Meant to apply on top of the previous one, but these two are
>    about separate and orthogonal issues.

I agree they are orthogonal in concept, though I doubt the symlink tests here would pass without the previous one (since verify_path does not know or care about crossing symlink boundaries).

-Peff