linux-kernel - Re: [PATCH] usbip: vudc: check for NULL before use

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Message-ID: <CAKocOOM-qOTJXfkDdr3GAgS3fXqLgHG=8ScA94nM=fkSzdCz0A@mail.gmail.com>
Date:   Wed, 21 Dec 2016 07:38:21 -0700
From:   Shuah Khan <shuahkhan@...il.com>
To:     Sudip Mukherjee <sudipm.mukherjee@...il.com>
Cc:     Shuah Khan <shuah@...nel.org>,
        Valentina Manea <valentina.manea.m@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        LKML <linux-kernel@...r.kernel.org>, linux-usb@...r.kernel.org,
        Shuah Khan <shuahkh@....samsung.com>,
        Shuah Khan <shuahkhan@...il.com>
Subject: Re: [PATCH] usbip: vudc: check for NULL before use

Hi Sudip,

On Wed, Dec 21, 2016 at 6:33 AM, Sudip Mukherjee
<sudipm.mukherjee@...il.com> wrote:
> On Tue, Dec 20, 2016 at 07:31:44AM -0700, Shuah Khan wrote:
>> On 12/18/2016 03:44 PM, Sudip Mukherjee wrote:
>> > to_vep() is doing a container_of() on _ep. It is better to do the NULL
>> > check first and then use it.
>> >
>> > Signed-off-by: Sudip Mukherjee <sudip.mukherjee@...ethink.co.uk>
>> > ---
>> >  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 968471b..32ea604 100644
>> > --- a/drivers/usb/usbip/vudc_dev.c
>> > +++ b/drivers/usb/usbip/vudc_dev.c
>> > @@ -388,10 +388,10 @@ static int vep_dequeue(struct usb_ep *_ep, struct usb_request *_req)
>> >     unsigned long flags;
>> >     int ret = 0;
>> >
>> > -   ep = to_vep(_ep);
>> >     if (!_ep)
>> >             return -EINVAL;
>>
>> Hmm. Linus's latest checks _ep and _req. Are you sure you are working
>> with the latest tree?
>
> I checked with next-20161221 and its still there.

This is for  vep_dequeue() - Are you sure both linux-next and Linus's tree show
the following:

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/usb/usbip/vudc_dev.c

static int vep_dequeue(struct usb_ep *_ep, struct usb_request *_req)
{
struct vep *ep;
struct vrequest *req;
struct vudc *udc;
struct vrequest *lst;
unsigned long flags;
int ret = -EINVAL;

if (!_ep || !_req)
return ret;

ep = to_vep(_ep);
req = to_vrequest(_req);
udc = req->udc;

if (!udc->driver)
return -ESHUTDOWN;

There are other routines in this file that don't check null. I am confused.

thanks,
-- Shuah