Re: [PATCH] usb: gadget: f_midi: Fixed a bug when buflen was smaller than wMaxPacketSize

[Clemens Ladisch]

Steve Calfee wrote:
> On Wed, Mar 9, 2016 at 11:39 AM, Felipe F. Tonello <eu@xxxxxxxxxxxxxxxxx> wrote:
>> [...]
>> This patch fixes this problem by setting the minimum usb_request's buffer size
>> for the OUT endpoint as its wMaxPacketSize.
>>
>> --- a/drivers/usb/gadget/function/f_midi.c
>> +++ b/drivers/usb/gadget/function/f_midi.c
>> @@ -366,7 +366,9 @@ static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
>>                 struct usb_request *req =
>> -                       midi_alloc_ep_req(midi->out_ep, midi->buflen);
>> +                       midi_alloc_ep_req(midi->out_ep,
>> +                               max_t(unsigned, midi->buflen,
>> +                                       bulk_out_desc.wMaxPacketSize));
>
> Won't you get a buffer overrun if midi->buflen is less than wMaxPacketSize?

No.  f_midi_handle_out_data() uses only the request buffer.


Regards,
Clemens