[Geany-Devel] CodeAi Fixes a Null Pointer Dereference

[Benjamin Bales]

Lex and Matthew,

You seem to disagree on this issue.  Is this a valid issue?  And if so, do
you like the fix?  I can batch a few of them (<= 10) as a single PR.  No
problem.

-Ben

On Wed, May 10, 2017 at 8:22 PM, Matthew Brush <mbrush at codebrainz.ca> wrote:

> On 2017-05-10 04:09 PM, Lex Trotman wrote:
>
>> On 11 May 2017 at 08:10, Benjamin Bales <benjamin.bales at qbitlogic.com>
>> wrote:
>>
>> CodeAi (https://github.com/C0deAi), an automated repair tool developed at
>>> QbitLogic (www.qbitlogic.com), suggested the following fix. Could I
>>> submit it as a patch if it looks alright?
>>>
>>> plugins/saveactions.c: “doc->file_type” pointer might be dereferenced
>>> when
>>> null on line 283.  Initialization may be provided by “doc” passed in as a
>>> function argument, but a null check would be prudent just in case. The
>>> fix
>>> checks “doc->file_type” for null before allowing a dereference on the
>>> following line.  A snapshot of the bug report generated by CodeAi is
>>> attached.  A full report is available upon request.
>>>
>>>
>> This function is called (via the signal framework) by the function that
>> created `doc` and as such cannot be null.  The design of the application
>> uses the signal framework to decouple caller and callee and this is likely
>> to confuse your tool since it cannot see where functions are called.
>> Whilst any contributions are welcome, a report with a lot of similar false
>> positives may end up being ignored and be a bad advertisement for your
>> tool.
>>
>>
> Naw, I think it's technically a real bug, albeit very minor. It's the
> `file_type` member of the `doc` that can be NULL. IIUC tools like this look
> to see if you checked the NULL-ness of something and then proceed to
> dereference it outside of that check later, which this code does (checks if
> `ft == NULL` several lines up and then unconditionally dereferences it on
> the line given by the OP).
>
> Regards,
> Matthew Brush
>
>
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Benjamin Bales
Chief Technology Officer
[image: QbitLogic]
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