[PATCH 02/13] drm/meson: dw-hdmi: Protect from possible NULL pointer dereference

[Neil Armstrong]

On 5/18/26 21:47, Jonas Karlman wrote:
> The IRQ handler can be called at any time after the call to
> devm_request_threaded_irq() completes, even before dw_hdmi->bridge has
> been assigned later in meson_dw_hdmi_bind().
> 
> Protect from a possible NULL pointer dereference in IRQ handler by only
> calling drm_helper_hpd_irq_event() when bridge has been assigned.
> 
> Fixes: e67f6037ae1b ("drm/meson: split out encoder from meson_dw_hdmi")
> Signed-off-by: Jonas Karlman <jonas at kwiboo.se>
> ---
> I only observed this NULL pointer dereference one time, without being
> able to reliably re-create a similar timing scenario. I still think this
> is an issue that possible could happen and likely should be fixed.
> 
> Note that patches later in this series will fully replace this change.
> ---
>   drivers/gpu/drm/meson/meson_dw_hdmi.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> index 993f6d5d4b29..eafe7daf6ff1 100644
> --- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
> +++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> @@ -520,7 +520,8 @@ static irqreturn_t dw_hdmi_top_thread_irq(int irq, void *dev_id)
>   	u32 stat = dw_hdmi->irq_stat;
>   
>   	/* HPD Events */
> -	if (stat & (HDMITX_TOP_INTR_HPD_RISE | HDMITX_TOP_INTR_HPD_FALL)) {
> +	if (stat & (HDMITX_TOP_INTR_HPD_RISE | HDMITX_TOP_INTR_HPD_FALL) &&
> +	    dw_hdmi->bridge) {
>   		bool hpd_connected = false;
>   
>   		if (stat & HDMITX_TOP_INTR_HPD_RISE)

Reviewed-by: Neil Armstrong <neil.armstrong at linaro.org>

Thanks,
Neil