Re: [PATCH] usbip: vudc: fix null pointer dereference on udc->lock

[Krzysztof Opasiak]

On 02/26/2018 05:40 PM, Shuah Khan wrote:
> On 02/22/2018 10:39 AM, Colin King wrote:
> > From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> >
> > Currently the driver attempts to spin lock on udc->lock before a NULL
> > pointer check is performed on udc, hence there is a potential null
> > pointer dereference on udc->lock.  Fix this by moving the null check
> > on udc before the lock occurs.
> >
> > Fixes: ea6873a45a22 ("usbip: vudc: Add SysFS infrastructure for VUDC")
> > Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> > ---
> >   drivers/usb/usbip/vudc_sysfs.c | 8 ++++++--
> >   1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/usb/usbip/vudc_sysfs.c b/drivers/usb/usbip/vudc_sysfs.c
> > index d86f72bbbb91..6dcd3ff655c3 100644
> > --- a/drivers/usb/usbip/vudc_sysfs.c
> > +++ b/drivers/usb/usbip/vudc_sysfs.c
> > @@ -105,10 +105,14 @@ static ssize_t usbip_sockfd_store(struct device *dev, struct device_attribute *a
> >   	if (rv != 0)
> >   		return -EINVAL;
> >   
> > +	if (!udc) {
> > +		dev_err(dev, "no device");
> > +		return -ENODEV;
> > +	}
> >   	spin_lock_irqsave(&udc->lock, flags);
> >   	/* Don't export what we don't have */
> > -	if (!udc || !udc->driver || !udc->pullup) {
> > -		dev_err(dev, "no device or gadget not bound");
> > +	if (!udc->driver || !udc->pullup) {
> > +		dev_err(dev, "gadget not bound");
> >   		ret = -ENODEV;
> >   		goto unlock;
> >   	}
>
> Thanks for the patch. Looks good to me.
>
> Acked-by: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>

Reviewed-by: Krzysztof Opasiak <k.opasiak@xxxxxxxxxxx>

but you could fix also a similar bug one one function above 
(dev_desc_read()) ;)

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