[PATCH] drm/mediatek: mtk_hdmi_v2: NULL check curr_conn in pre_enable

[PATCH] drm/mediatek: mtk_hdmi_v2: NULL check curr_conn in pre_enable

[Tang Bin]

mtk_hdmi_v2_bridge_pre_enable() calls
drm_atomic_get_new_connector_state(state, hdmi->curr_conn) which
dereferences hdmi->curr_conn (via drm_connector_index) before the existing
WARN_ON(!conn_state) check. Add WARN_ON(!hdmi->curr_conn) first.

Fixes: 8d0f79886273 ("drm/mediatek: Introduce HDMI/DDC v2 for MT8195/MT8188")
Cc: stable@vger.kernel.org
Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
---
 drivers/gpu/drm/mediatek/mtk_hdmi_v2.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi_v2.c b/drivers/gpu/drm/mediatek/mtk_hdmi_v2.c
index f0277fcf3..c94d22042 100644
--- a/drivers/gpu/drm/mediatek/mtk_hdmi_v2.c
+++ b/drivers/gpu/drm/mediatek/mtk_hdmi_v2.c
@@ -1026,6 +1026,8 @@ static void mtk_hdmi_v2_bridge_pre_enable(struct drm_bridge *bridge,
 
 	/* Retrieve the connector through the atomic state */
 	hdmi->curr_conn = drm_atomic_get_new_connector_for_encoder(state, bridge->encoder);
+	if (WARN_ON(!hdmi->curr_conn))
+		return;
 
 	conn_state = drm_atomic_get_new_connector_state(state, hdmi->curr_conn);
 	if (WARN_ON(!conn_state))
-- 
2.52.0.windows.1

Re: [PATCH] drm/mediatek: mtk_hdmi_v2: NULL check curr_conn in pre_enable

[CK Hu (胡俊光)]

On Tue, 2026-10-27 at 17:49 +0800, Tang Bin wrote:
> External email : Please do not click links or open attachments until you have verified the sender or the content.
> 
> 
> mtk_hdmi_v2_bridge_pre_enable() calls
> drm_atomic_get_new_connector_state(state, hdmi->curr_conn) which
> dereferences hdmi->curr_conn (via drm_connector_index) before the existing
> WARN_ON(!conn_state) check. Add WARN_ON(!hdmi->curr_conn) first.
> 
> Fixes: 8d0f79886273 ("drm/mediatek: Introduce HDMI/DDC v2 for MT8195/MT8188")
> Cc: stable@vger.kernel.org
> Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_hdmi_v2.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi_v2.c b/drivers/gpu/drm/mediatek/mtk_hdmi_v2.c
> index f0277fcf3..c94d22042 100644
> --- a/drivers/gpu/drm/mediatek/mtk_hdmi_v2.c
> +++ b/drivers/gpu/drm/mediatek/mtk_hdmi_v2.c
> @@ -1026,6 +1026,8 @@ static void mtk_hdmi_v2_bridge_pre_enable(struct drm_bridge *bridge,
> 
>         /* Retrieve the connector through the atomic state */
>         hdmi->curr_conn = drm_atomic_get_new_connector_for_encoder(state, bridge->encoder);
> +       if (WARN_ON(!hdmi->curr_conn))
> +               return;

In drm_atomic_helper_commit_encoder_bridge_pre_enable(),
it already ensure drm_atomic_get_new_connector_for_encoder() would not return NULL,
so I would like not to check here to prevent numerous checking.

Regards,
CK

> 
>         conn_state = drm_atomic_get_new_connector_state(state, hdmi->curr_conn);
>         if (WARN_ON(!conn_state))
> --
> 2.52.0.windows.1
> 
> 
> 
>