Re: [PATCH v5 14/19] drm/hdmi: Rename __drm_atomic_helper_connector_hdmi_reset()

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] __drm_atomic_helper_connector_hdmi_state_init() dereferences new_conn_state without a NULL check, leading to a kernel panic if state allocation fails in drm_atomic_helper_connector_reset(). This problem wasn't introduced by this patch, but existed in the previous implementation.
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commit ca36932b2899a887d5e634584333e43a5290dc5b
Author: Maxime Ripard <mripard@kernel.org>

drm/hdmi: Rename __drm_atomic_helper_connector_hdmi_reset()

This commit renames __drm_atomic_helper_connector_hdmi_reset() to
__drm_atomic_helper_connector_hdmi_state_init(). This prepares for
consolidating DRM objects state allocation around the atomic_create_state
callback.

> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index a161d3b00a255..74dce4be0c008 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -508,7 +508,7 @@ static int vc4_hdmi_connector_atomic_check(struct drm_connector *connector,
>  static void vc4_hdmi_connector_reset(struct drm_connector *connector)
>  {
>  	drm_atomic_helper_connector_reset(connector);
> -	__drm_atomic_helper_connector_hdmi_reset(connector, connector->state);
> +	__drm_atomic_helper_connector_hdmi_state_init(connector, connector->state);

Can this result in a NULL pointer dereference if memory allocation fails?

This problem appears to have existed prior to this patch, but remains present.

If kzalloc_obj() fails inside drm_atomic_helper_connector_reset(), it will
set connector->state to NULL. This NULL pointer is then passed into
__drm_atomic_helper_connector_hdmi_state_init():

void __drm_atomic_helper_connector_hdmi_state_init(...,
						   struct drm_connector_state *new_conn_state)
{
	...
	new_conn_state->max_bpc = max_bpc;
	...
}

Does this code need a check for new_conn_state before dereferencing it,
or should the caller check if connector->state is valid before calling this
initialization function?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260519-drm-mode-config-init-v5-0-388b03321e38@kernel.org?part=14