[PATCH] gpu: drm: radeon: Fix a possible null-pointer dereference in radeon_connector_set_property()

[Alex Deucher]

On Mon, Jul 29, 2019 at 11:08 AM Jia-Ju Bai <baijiaju1990 at gmail.com> wrote:
>
> In radeon_connector_set_property(), there is an if statement on line 743
> to check whether connector->encoder is NULL:
>     if (connector->encoder)
>
> When connector->encoder is NULL, it is used on line 755:
>     if (connector->encoder->crtc)
>
> Thus, a possible null-pointer dereference may occur.
>
> To fix this bug, connector->encoder is checked before being used.
>
> This bug is found by a static analysis tool STCheck written by us.

I believe we always have an encoder for every connector, but never
hurts to be safe.  Thanks.  Applied.

Alex

>
> Signed-off-by: Jia-Ju Bai <baijiaju1990 at gmail.com>
> ---
>  drivers/gpu/drm/radeon/radeon_connectors.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
> index c60d1a44d22a..b684cd719612 100644
> --- a/drivers/gpu/drm/radeon/radeon_connectors.c
> +++ b/drivers/gpu/drm/radeon/radeon_connectors.c
> @@ -752,7 +752,7 @@ static int radeon_connector_set_property(struct drm_connector *connector, struct
>
>                 radeon_encoder->output_csc = val;
>
> -               if (connector->encoder->crtc) {
> +               if (connector->encoder && connector->encoder->crtc) {
>                         struct drm_crtc *crtc  = connector->encoder->crtc;
>                         struct radeon_crtc *radeon_crtc = to_radeon_crtc(crtc);
>
> --
> 2.17.0
>
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