[PATCH v5 4/9] drm/vc4: hdmi: Don't access the connector state in reset if kmalloc fails

[Dave Stevenson]

Hi Maxime

On Mon, 7 Dec 2020 at 15:57, Maxime Ripard <maxime at cerno.tech> wrote:
>
> drm_atomic_helper_connector_reset uses kmalloc which, from an API
> standpoint, can fail, and thus setting connector->state to NULL.
> However, our reset hook then calls drm_atomic_helper_connector_tv_reset
> that will access connector->state without checking if it's a valid
> pointer or not.
>
> Make sure we don't end up accessing a NULL pointer.
>
> Acked-by: Thomas Zimmermann <tzimmermann at suse.de>
> Suggested-by: Dave Stevenson <dave.stevenson at raspberrypi.com>
> Signed-off-by: Maxime Ripard <maxime at cerno.tech>

Reviewed-by: Dave Stevenson <dave.stevenson at raspberrypi.com>

> ---
>  drivers/gpu/drm/vc4/vc4_hdmi.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index a88aa20beeb6..61039cc89d9d 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -171,7 +171,9 @@ static int vc4_hdmi_connector_get_modes(struct drm_connector *connector)
>  static void vc4_hdmi_connector_reset(struct drm_connector *connector)
>  {
>         drm_atomic_helper_connector_reset(connector);
> -       drm_atomic_helper_connector_tv_reset(connector);
> +
> +       if (connector->state)
> +               drm_atomic_helper_connector_tv_reset(connector);
>  }
>
>  static const struct drm_connector_funcs vc4_hdmi_connector_funcs = {
> --
> 2.28.0
>