On 01/31/2017 04:56 PM, Felipe Balbi wrote:
>
> Hi,
>
> Krzysztof Opasiak <k.opasiak@xxxxxxxxxxx> writes:
>> On 01/31/2017 02:08 PM, Felipe Balbi wrote:
>>> If we're dealing with SuperSpeed endpoints, we need
>>> to make sure to pass along the companion descriptor
>>> and initialize fields needed by the Gadget
>>> API. Eventually, f_fs.c should be converted to use
>>> config_ep_by_speed() like all other functions,
>>> though.
>>>
>>> Cc: <stable@xxxxxxxxxxxxxxx>
>>> Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
>>> ---
>>>
>>> Will be sent in a pull request during v4.11-rc
>>>
>>> drivers/usb/gadget/function/f_fs.c | 15 +++++++++++++--
>>> 1 file changed, 13 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
>>> index 87fccf611b69..86aba2ebb3ef 100644
>>> --- a/drivers/usb/gadget/function/f_fs.c
>>> +++ b/drivers/usb/gadget/function/f_fs.c
>>> @@ -1833,11 +1833,14 @@ static int ffs_func_eps_enable(struct ffs_function *func)
>>> spin_lock_irqsave(&func->ffs->eps_lock, flags);
>>> while(count--) {
>>> struct usb_endpoint_descriptor *ds;
>>> + struct usb_ss_ep_comp_descriptor *comp_desc = NULL;
>>> + int needs_comp_desc = false;
>>> int desc_idx;
>>>
>>> - if (ffs->gadget->speed == USB_SPEED_SUPER)
>>> + if (ffs->gadget->speed == USB_SPEED_SUPER) {
>>> desc_idx = 2;
>>> - else if (ffs->gadget->speed == USB_SPEED_HIGH)
>>> + needs_comp_desc = true;
>>> + } else if (ffs->gadget->speed == USB_SPEED_HIGH)
>>> desc_idx = 1;
>>> else
>>> desc_idx = 0;
>>> @@ -1854,6 +1857,14 @@ static int ffs_func_eps_enable(struct ffs_function *func)
>>>
>>> ep->ep->driver_data = ep;
>>> ep->ep->desc = ds;
>>> +
>>> + comp_desc = (struct usb_ss_ep_comp_descriptor *)(ds +
>>> + USB_DT_ENDPOINT_SIZE);
>>> + ep->ep->maxburst = comp_desc->bMaxBurst + 1;
>>> +
>>> + if (needs_comp_desc)
>>> + ep->ep->comp_desc = comp_desc;
>>> +
>>
>> Please correct me if I'm wrong but wouldn't we read rubbish here if user
>> provided us SS ep descriptor without companion descriptor?
>
> companion desc is required for SS endpoints, it's also required that
> they follow EP desc. If user doesn't write it, don't they deserve the
> errors they'll have?
>
But do we deserve to access potentially unallocated memory inside kernel
each time when some malicious application requests this?;)
In my humble opinion user should get -EINVAL or sth like this from
write(desc, sizeof(desc)) instead of some random data in companion
descriptor.
Cheers,
--
Krzysztof Opasiak
Samsung R&D Institute Poland
Samsung Electronics
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