[PATCH] fopencookie: Mangle function pointers stored on the heap [BZ #20222]

[Carlos O'Donell]

On 06/10/2016 11:56 AM, Florian Weimer wrote:
> On 06/10/2016 05:55 PM, Carlos O'Donell wrote:
> 
>>> +/* Copy the callbacks from SOURCE to *TARGET, with pointer
>>> +   mangling.  */
>>> +static void
>>> +set_callbacks (_IO_cookie_io_functions_t *target,
>>> +           _IO_cookie_io_functions_t source)
>>> +{
>>> +  PTR_MANGLE (source.read);
>>> +  PTR_MANGLE (source.write);
>>> +  PTR_MANGLE (source.seek);
>>> +  PTR_MANGLE (source.close);
>>
>> Isn't this modifying the user's copy of the callbacks
>> passed in during the call to fopencookie?
> 
> No, C function arguments are pass-by-value. It's not a
> pointer-to-struct, it's the struct object itself.

Sorry yes, I misread that as pointer-to-struct.

You are absolutely right, these are just struct copies
being passed around so we don't care.

Patch looks good to me then.

-- 
Cheers,
Carlos.