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

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Message-ID: <20190125080227.GA21576@kroah.com>
Date:   Fri, 25 Jan 2019 09:02:27 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     shuah <shuah@...nel.org>
Cc:     Shuah Khan <skhan@...uxfoundation.org>,
        valentina.manea.m@...il.com, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usbip: Fix vep_free_request() null pointer checks on
 input args

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,

greg k-h