Re: user accesses in ivtv-fileops.c:ivtv_v4l2_write ?

["Dr. David Alan Gilbert" <linux@treblig.org>]

* Andy Walls (awalls@md.metrocast.net) wrote:
> On Sun, 2011-01-09 at 00:34 +0000, Dr. David Alan Gilbert wrote:
> > Hi Andy,
> >   It looks like we missed something in that copy from user
> > patch from the end of last year:
> > 
> > +void ivtv_write_vbi_from_user(struct ivtv *itv,
> > +                             const struct v4l2_sliced_vbi_data __user *sliced,
> > +                             size_t cnt)
> > +{
> > +       struct vbi_cc cc = { .odd = { 0x80, 0x80 }, .even = { 0x80, 0x80 } };
> > +       int found_cc = 0;
> > +       size_t i;
> > +       struct v4l2_sliced_vbi_data d;
> > +
> > +       for (i = 0; i < cnt; i++) {
> > +               if (copy_from_user(&d, sliced + i,
> > +                                  sizeof(struct v4l2_sliced_vbi_data)))
> > +                       break;
> > +               ivtv_write_vbi_line(itv, sliced + i, &cc, &found_cc);
>                                            ^^^^^^^^^^
> What was I thinking?  ---------------------+
> 
> Decent plan; failed execution. :(

Sorry for not spotting it when you sent it out last time!

> > sparse is giving me:
> > drivers/media/video/ivtv/ivtv-vbi.c:177:49: warning: incorrect type in argument 2 (different address spaces)
> > drivers/media/video/ivtv/ivtv-vbi.c:177:49:    expected struct v4l2_sliced_vbi_data const *d
> > drivers/media/video/ivtv/ivtv-vbi.c:177:49:    got struct v4l2_sliced_vbi_data const [noderef] <asn:1>*
> > 
> > and I think the point is that while you've copied the data I think
> > you're still passing the user pointer to ivtv_write_vbi_line and it 
> > should be:
> > 
> >                ivtv_write_vbi_line(itv, &d, &cc, &found_cc);
> > 
> > 
> > What do you think?
> 
> Yes, it looks like I gooned that one up. :)
> 
> That's what I get for trying to fix things with the kids running around
> before bedtime.
> 
> I assume that you have made the replacement and tested that sparse is
> satisfied?

Yes, seems happy - of course I thought I did last time :-)

Dave
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