Re: [ldv-project] [PATCH v2] usb: cdns3: change place of 'priv_ep' assignment in cdns3_gadget_ep_dequeue(), cdns3_gadget_ep_enable()

[Alexey Khoroshilov <khoroshilov@ispras.ru>]

On 27.07.2022 11:39, Peter Chen wrote:
> On 22-07-18 19:00:52, Andrey Strachuk wrote:
>> If 'ep' is NULL, result of ep_to_cdns3_ep(ep) is invalid pointer
>> and its dereference with priv_ep->cdns3_dev may cause panic.
>>
>> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>>
>> Signed-off-by: Andrey Strachuk <strochuk@ispras.ru>
>> Fixes: 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver")
>> ---
>>  drivers/usb/cdns3/cdns3-gadget.c | 9 ++++++---
>>  1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
>> index 5c15c48952a6..aea5db0ec72d 100644
>> --- a/drivers/usb/cdns3/cdns3-gadget.c
>> +++ b/drivers/usb/cdns3/cdns3-gadget.c
>> @@ -2285,13 +2285,14 @@ static int cdns3_gadget_ep_enable(struct usb_ep *ep,
>>  	int val;
>>
>>  	priv_ep = ep_to_cdns3_ep(ep);
>> -	priv_dev = priv_ep->cdns3_dev;
>> -	comp_desc = priv_ep->endpoint.comp_desc;
>>  
>>  	if (!ep || !desc || desc->bDescriptorType != USB_DT_ENDPOINT) {
>>  		dev_dbg(priv_dev->dev, "usbss: invalid parameters\n");
>>  		return -EINVAL;
>>  	}
>> +
>> +	comp_desc = priv_ep->endpoint.comp_desc;
>> +	priv_dev = priv_ep->cdns3_dev;
>>
>>  	if (!desc->wMaxPacketSize) {
>>  		dev_err(priv_dev->dev, "usbss: missing wMaxPacketSize\n");
>> @@ -2600,7 +2601,7 @@ int cdns3_gadget_ep_dequeue(struct usb_ep *ep,
>>  			    struct usb_request *request)
>>  {
>>  	struct cdns3_endpoint *priv_ep = ep_to_cdns3_ep(ep);
>> -	struct cdns3_device *priv_dev = priv_ep->cdns3_dev;
>> +	struct cdns3_device *priv_dev;
>>  	struct usb_request *req, *req_temp;
>>  	struct cdns3_request *priv_req;
>>  	struct cdns3_trb *link_trb;
>> @@ -2610,6 +2611,8 @@ int cdns3_gadget_ep_dequeue(struct usb_ep *ep,
>>  
>>  	if (!ep || !request || !ep->desc)
>>  		return -EINVAL;
>> +
>> +	priv_dev = priv_ep->cdns3_dev;
>>
>>  	spin_lock_irqsave(&priv_dev->lock, flags);
>>
>> -- 
> 
> Acked-by: Peter Chen <peter.chen@kernel.org>
> 

Looks good, but I would suggest to move

  priv_ep = ep_to_cdns3_ep(ep);

below the check of 'ep' as well.

--
Alexey