Re: [PATCH v1] media: media_device_enum_links32: fix missing reserved field copy

[Jungo Lin <jungo.lin@mediatek.com>]

Hi, Laurent,

On Tue, 2019-04-02 at 14:33 +0300, Laurent Pinchart wrote:
> Hi Jungo,
> 
> Thank you for the patch.
> 
> On Tue, Apr 02, 2019 at 06:04:04PM +0800, Jungo Lin wrote:
> > From: Jungo Lin <jungo.lin@mediatek.corp-partner.google.com>
> > 
> > In v4l2-compliance utility, test MEDIA_IOC_ENUM_ENTITIES
> > will check whether reserved field of media_links_enum filled
> > with zero. Reserved field is filled with zero in media_device_enum_links.
> > 
> > However, for 32 bit program, the reserved field is missing
> > copy from kernel space to user space in media_device_enum_links32
> > function.
> > 
> > This patch copies reserved field of media_links_enum from kernel space
> > to user space.
> > 
> > Signed-off-by: Jungo Lin <jungo.lin@mediatek.com>
> > ---
> >  drivers/media/media-device.c | 11 ++++++++++-
> >  1 file changed, 10 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
> > index b8ec886..f420829 100644
> > --- a/drivers/media/media-device.c
> > +++ b/drivers/media/media-device.c
> > @@ -502,6 +502,7 @@ static long media_device_enum_links32(struct media_device *mdev,
> >  {
> >  	struct media_links_enum links;
> >  	compat_uptr_t pads_ptr, links_ptr;
> > +	int ret;
> >  
> >  	memset(&links, 0, sizeof(links));
> >  
> > @@ -513,7 +514,15 @@ static long media_device_enum_links32(struct media_device *mdev,
> >  	links.pads = compat_ptr(pads_ptr);
> >  	links.links = compat_ptr(links_ptr);
> >  
> > -	return media_device_enum_links(mdev, &links);
> > +	ret = media_device_enum_links(mdev, &links);
> > +	if (ret)
> > +		return ret;
> > +
> > +	if (copy_to_user(ulinks->reserved, &links.reserved,
> > +			 sizeof(links.reserved)))
> > +		return -EFAULT;
> 
> I think it would be better to zero the reserved field here instead of
> copying it, as we know it has to be zero.
> 

Got it.
We will revise the implementation and deliver the v2 patch.

Thanks,

Jungo 

> > +
> > +	return 0;
> >  }
> >  
> >  #define MEDIA_IOC_ENUM_LINKS32		_IOWR('|', 0x02, struct media_links_enum32)
>