linux-kernel - Re: [PATCH] usbip: Fix vep_free_request() null pointer checks on input args

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Message-ID: <0d292f37-0584-2d95-605f-7741e845c73f@kernel.org>
Date:   Fri, 25 Jan 2019 07:26:57 -0700
From:   shuah <shuah@...nel.org>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Shuah Khan <skhan@...uxfoundation.org>,
        valentina.manea.m@...il.com, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, shuah <shuah@...nel.org>
Subject: Re: [PATCH] usbip: Fix vep_free_request() null pointer checks on
 input args

On 1/25/19 1:02 AM, Greg KH wrote:
> On Tue, Jan 22, 2019 at 04:05:28PM -0700, shuah wrote:
>> On 1/19/19 1:17 AM, Greg KH wrote:
>>> On Fri, Jan 18, 2019 at 02:29:30PM -0700, Shuah Khan wrote:
>>>> From: Shuah Khan <shuah@...nel.org>
>>>>
>>>> Fix vep_free_request() to return when usb_ep and usb_request are null
>>>> instead of calling WARN_ON.
>>>>
>>>> Signed-off-by: Shuah Khan <shuah@...nel.org>
>>>> ---
>>>>    drivers/usb/usbip/vudc_dev.c | 2 +-
>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/usb/usbip/vudc_dev.c b/drivers/usb/usbip/vudc_dev.c
>>>> index 1634d8698e15..bfc8218e3fb6 100644
>>>> --- a/drivers/usb/usbip/vudc_dev.c
>>>> +++ b/drivers/usb/usbip/vudc_dev.c
>>>> @@ -297,7 +297,7 @@ static void vep_free_request(struct usb_ep *_ep, struct usb_request *_req)
>>>>    {
>>>>    	struct vrequest *req;
>>>> -	if (WARN_ON(!_ep || !_req))
>>>> +	if (!_ep || !_req)
>>>
>>> It's impossible for _ep to be NULL in this callback (see
>>> usb_ep_free_request() for where this is called from to prove that), so I
>>> don't think you need to check that.  It's almost impossible for _req to
>>> be NULL, so you might as well leave that check in.
>>>
>>
>> Yes. ep can never be null here in vep_free_request(). I will leave
>> this alone.
> 
> You can drop the !_ep check at the least, no need to check something
> that is impossible to hit :)
> 

Thanks. I will do that.

-- Shuah