Re: [PATCH 0/2] Fix crashes due to real_pathdup() potentially returning NULL

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Mar 9, 2017, 11:26 UTC
Message-ID: <alpine.DEB.2.20.1703091224360.3767@virtualbox>
In-Reply-To: <20170308161742.lpbf6gn6qhoex7et@sigill.intra.peff.net>

Hi Peff,

On Wed, 8 Mar 2017, Jeff King wrote:

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> On Wed, Mar 08, 2017 at 04:43:27PM +0100, Johannes Schindelin wrote:
> 
> > We may want to consider fast-tracking this into v2.12.1, and to that
> > end, I would appreciate code reviews that focus on the correctness of
> > this patch and that try to consider undesired side effects.
> 
> I don't see how it could be not-correct, in the sense that every caller
> now passes the die_on_error flag (restoring the original behavior)
> except for the one which clearly checks for a NULL return immediately
> afterward.

Indeed. The principal reason why I extended the function signature was so that any bugs would become obvious.

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> The only exception would be if there were new calls to real_pathdup()
> that did not originally use real_path(). But:
> 
>   # 7241764076 introduced real_pathdup
>   git log -Sreal_pathdup 7241764076..
> 
> shows only one other introduction, and it's just duplicating an existing
> call.

Thanks for digging that up. I really only looked at the existing code in `master` to figure out whether the return values were checked against NULL or not.

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> It's possible that some of these _could_ handle the error case more
> gracefully (I already fixed one such case in 3a1345af2). But even if
> we wanted to do so, that should come separately on top of this patch.
> This can go to 'maint' as a regression fix, and then that gives a stable
> base for making potential improvements.

Fully agree.

Thank you for the thorough review, Johannes