linux-kernel - Re: [ldv-project] [PATCH v2] usb: cdns3: change place of 'priv_ep' assignment in cdns3_gadget_ep_dequeue(), cdns3_gadget_ep

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Message-ID: <370caacd-6e03-8c8c-1ea6-0beef763fee6@ispras.ru>
Date:   Wed, 27 Jul 2022 12:03:38 +0300
From:   Alexey Khoroshilov <khoroshilov@...ras.ru>
To:     Peter Chen <peter.chen@...nel.org>,
        Andrey Strachuk <strochuk@...ras.ru>
Cc:     ldv-project@...uxtesting.org, Pawel Laszczak <pawell@...ence.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Roger Quadros <rogerq@...nel.org>,
        Aswath Govindraju <a-govindraju@...com>
Subject: Re: [ldv-project] [PATCH v2] usb: cdns3: change place of 'priv_ep'
 assignment in cdns3_gadget_ep_dequeue(), cdns3_gadget_ep_enable()

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@...ras.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@...nel.org>
> 

Looks good, but I would suggest to move

  priv_ep = ep_to_cdns3_ep(ep);

below the check of 'ep' as well.

--
Alexey