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[PATCH] usbip: vudc: check for NULL before use

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  [PATCH] usbip: vudc: check for NULL before use Sudip Mukherjee <sudipm.mukherjee@gmail.com> - 2016-12-18 23:50 +0100
    Re: [PATCH] usbip: vudc: check for NULL before use Shuah Khan <shuah@kernel.org> - 2016-12-20 15:40 +0100
      Re: [PATCH] usbip: vudc: check for NULL before use Sudip Mukherjee <sudipm.mukherjee@gmail.com> - 2016-12-21 14:40 +0100
        Re: [PATCH] usbip: vudc: check for NULL before use Shuah Khan <shuahkhan@gmail.com> - 2016-12-21 15:40 +0100
          Re: [PATCH] usbip: vudc: check for NULL before use Krzysztof Opasiak <k.opasiak@samsung.com> - 2016-12-21 16:10 +0100
          Re: [PATCH] usbip: vudc: check for NULL before use Sudip Mukherjee <sudipm.mukherjee@gmail.com> - 2016-12-21 17:30 +0100

#1544216 — [PATCH] usbip: vudc: check for NULL before use

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@codethink.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;
 
+	ep = to_vep(_ep);
 	udc = ep_to_vudc(ep);
 	if (!udc->driver)
 		return -ESHUTDOWN;
-- 
1.9.1

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#1545168

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@codethink.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?

>  
> +	ep = to_vep(_ep);
>  	udc = ep_to_vudc(ep);
>  	if (!udc->driver)
>  		return -ESHUTDOWN;
>

thanks,
-- Shuah

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#1545769

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@codethink.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.

regards
sudip

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#1545799

Hi Sudip,

On Wed, Dec 21, 2016 at 6:33 AM, Sudip Mukherjee
<sudipm.mukherjee@gmail.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@codethink.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

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#1545823

Hi,

On 12/21/2016 03:38 PM, Shuah Khan wrote:
> Hi Sudip,
> 
> On Wed, Dec 21, 2016 at 6:33 AM, Sudip Mukherjee
> <sudipm.mukherjee@gmail.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@codethink.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.
> 

generally this file contains implementation of gadget/endpoint
callbacks. Those methods will be called by udc-core with values passed
from USB gadget (usually directly from function).

I check other udc in kernel and there is no agreement if we should check
in those callbacks if our params are NULL or not.

I have also run through udc-core implementation and generally it doesn't
check if params are NULL or not and just dereference some of them and
pass them to our callbacks.

I think that the best option is just to ask Felipe (USB gadget
maintainer) if we should check this or not.


@Felipe
Should each UDC check if values passed to gadget/endpoint callbacks is
not NULL or just simply dereference them?


Best regards,
-- 
Krzysztof Opasiak
Samsung R&D Institute Poland
Samsung Electronics

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#1545858

On Wed, Dec 21, 2016 at 07:38:21AM -0700, Shuah Khan wrote:
> Hi Sudip,
> 
> On Wed, Dec 21, 2016 at 6:33 AM, Sudip Mukherjee
> <sudipm.mukherjee@gmail.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@codethink.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:

This is for vep_set_halt_and_wedge(). I do not have any idea why the
patch says its vep_dequeue(). I tried generating the patch again and
it still shows as vep_dequeue(). But the line number 388 is correct and
if you try to apply, it applies correctly.

regards
sudip

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