Re: [PATCH 2/3] ALSA: control: add dimension validator for userspace element

[Takashi Sakamoto <o-takashi@sakamocchi.jp>]

On Jul 1 2016 18:52, Takashi Iwai wrote:
>>>> Were I you, I would insert codes to evaluate the element of dimension
>>>> info; i.e.
>>>>
>>>>                 if (info->dimen.d[i] > 512)
>>>>                         break;
>>>>
>>>> Here, 512 is the maximum number of members which an element can have. In
>>>> this case, it's certainly an element of byte type.
>>>
>>> It's superfluous.  If info->count is already a sane value, it'd be
>>> enough to compare with this.
>>
>> The info->count comes from userspace or each driver. It's dangerous to
>> use it for avoiding arithmetic overflow.
> 
> Your function is to verify the dimen array.  And for that, a sane
> info->count value is prerequisite.  Otherwise how can you validate it
> at all...?

Hm.

There's a large difference between us for the design of this local
function. You're interested in the result of calculation, while I
consider about the soundness of whole members in the dimension info.

In this time, I'll follow your insistence. I'd like to save my time
against this long-abandoned feature.


Regards

Takashi Sakamoto