Re: [patch 1/3] vfio-mdev: return -EFAULT if copy_to_user() fails

[Alex Williamson <alex.williamson@redhat.com>]

On Tue, 10 Jan 2017 00:07:23 +0530
Kirti Wankhede <kwankhede@nvidia.com> wrote:

> CC+= Alex to pull this change.
> 
> Reviewed by: Kirti Wankhede <kwankhede@nvidia.com>

Thanks Dan.  Applied all three to for-linus for v4.10 with Kirti's R-b.
Thanks,

Alex

> On 1/7/2017 11:57 AM, Dan Carpenter wrote:
> > The copy_to_user() function returns the number of bytes which it wasn't
> > able to copy but we want to return a negative error code.
> > 
> > Fixes: 9d1a546c53b4 ("docs: Sample driver to demonstrate how to use Mediated device framework.")
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > 
> > diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
> > index 919c10d5b12e..d2656ff569c1 100644
> > --- a/samples/vfio-mdev/mtty.c
> > +++ b/samples/vfio-mdev/mtty.c
> > @@ -1180,7 +1180,10 @@ static long mtty_ioctl(struct mdev_device *mdev, unsigned int cmd,
> >  
> >  		memcpy(&mdev_state->dev_info, &info, sizeof(info));
> >  
> > -		return copy_to_user((void __user *)arg, &info, minsz);
> > +		if (copy_to_user((void __user *)arg, &info, minsz))
> > +			return -EFAULT;
> > +
> > +		return 0;
> >  	}
> >  	case VFIO_DEVICE_GET_REGION_INFO:
> >  	{
> > @@ -1201,7 +1204,10 @@ static long mtty_ioctl(struct mdev_device *mdev, unsigned int cmd,
> >  		if (ret)
> >  			return ret;
> >  
> > -		return copy_to_user((void __user *)arg, &info, minsz);
> > +		if (copy_to_user((void __user *)arg, &info, minsz))
> > +			return -EFAULT;
> > +
> > +		return 0;
> >  	}
> >  
> >  	case VFIO_DEVICE_GET_IRQ_INFO:
> > @@ -1224,7 +1230,10 @@ static long mtty_ioctl(struct mdev_device *mdev, unsigned int cmd,
> >  		if (info.count = -1)
> >  			return -EINVAL;
> >  
> > -		return copy_to_user((void __user *)arg, &info, minsz);
> > +		if (copy_to_user((void __user *)arg, &info, minsz))
> > +			return -EFAULT;
> > +
> > +		return 0;
> >  	}
> >  	case VFIO_DEVICE_SET_IRQS:
> >  	{
> >   
> --
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