Segmentation fault in notmuch search --format=json

[Jameson Graef Rollins]

On Tue, Aug 07 2012, Mark Walters <markwalters1009 at gmail.com> wrote:
> On Tue, 07 Aug 2012, Ben Gamari <bgamari.foss at gmail.com> wrote:
>> It seems some messages trigger a segmentation fault in
>> `do_search_threads()`. It appears the problem occurs (at least) when
>> `authors` is NULL.
>
> Hi thanks for the bug report and detailed debugging. I think I can see
> the problem and there is a test patch to fix it below, and this does
> appear to be a regression.
>
> In json.c the function json_quote_str explicitly checks/allows for a
> NULL pointer passed as a string and pretends it is just an empty
> string. That behaviour was lost in the move to structured formatters.
>
> A simple fix is to put this check for a null pointer in json_string in
> sprinter-json.c which is what this patch does.

Thanks Mark!  I was experiencing the same problem and this fixed the
issue before I even got a chance to respond.  This seems like a fine
solution.

> Incidentally this is the second time this bug has appeared: 
>
>         commit cacefbf3d6dd5bce0b60b3cdfce29bfa371dfaea
>         Author: David Edmondson <dme at dme.org>
>         Date:   Tue Apr 6 08:24:00 2010 +0100
>
>             json: Avoid calling strlen(NULL)
>                 
>                     MIME parts may have no filename, which previously resulted in calling
>                         strlen(NULL).
>
> so it really might be worth having a test for it!

Indeed!  I think the problematic email in this case was one with no
subject.

> Finally, I think nothing in json.c is used anymore so perhaps it
>  could be removed.

Agreed.

jamie.
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