Re: [PATCH v5 3/3] drm: protect drm_master pointers in drm_lease.c

[Desmond Cheong Zhi Xi]

On 30/6/21 8:16 am, Emil Velikov wrote:
> Hi Desmond,
>
> Couple of small suggestions, with those the series is:
> Reviewed-by: Emil Velikov <emil.l.velikov@xxxxxxxxx>
>
> On Tue, 29 Jun 2021 at 04:38, Desmond Cheong Zhi Xi
> <desmondcheongzx@xxxxxxxxx> wrote:
>
> > @@ -128,13 +137,20 @@ bool drm_lease_held(struct drm_file *file_priv, int id)
> >          struct drm_master *master;
> >          bool ret;
> >
> > -       if (!file_priv || !file_priv->master || !file_priv->master->lessor)
> > +       if (!file_priv)
> >                  return true;
> >
> > -       master = file_priv->master;
> > +       master = drm_file_get_master(file_priv);
> > +       if (master == NULL)
> > +               return true;
> > +       if (!master->lessor) {
> > +               drm_master_put(&master);
> > +               return true;
>
> Let's add a "ret = true; goto unlock;" here, so we can have a single
> drm_master_put() in the function.
> Nearly all code paths touched by this patch already follow this approach.
>
> > @@ -154,10 +170,16 @@ uint32_t drm_lease_filter_crtcs(struct drm_file *file_priv, uint32_t crtcs_in)
> >          int count_in, count_out;
> >          uint32_t crtcs_out = 0;
> >
> > -       if (!file_priv || !file_priv->master || !file_priv->master->lessor)
> > +       if (!file_priv)
> >                  return crtcs_in;
> >
> > -       master = file_priv->master;
> > +       master = drm_file_get_master(file_priv);
> > +       if (master == NULL)
> > +               return crtcs_in;
> > +       if (!master->lessor) {
> > +               drm_master_put(&master);
> > +               return crtcs_in;
>
> Ditto
>
> Thanks
> Emil

Sounds good to me, I'll revise these functions. Thanks for the review 
and suggestions, Emil.

Best wishes,
Desmond