Re: [PATCH] drm/amd/display: Add null pointer check in mod_hdcp_hdcp1_create_session()

[Alex Hung <alex.hung@amd.com>]

Reviewed-by: Alex Hung <alex.hung@amd.com>

On 7/23/25 20:36, Chenyuan Yang wrote:
> The function mod_hdcp_hdcp1_create_session() calls the function
> get_first_active_display(), but does not check its return value.
> The return value is a null pointer if the display list is empty.
> This will lead to a null pointer dereference.
> 
> Add a null pointer check for get_first_active_display() and return
> MOD_HDCP_STATUS_DISPLAY_NOT_FOUND if the function return null.
> 
> This is similar to the commit c3e9826a2202
> ("drm/amd/display: Add null pointer check for get_first_active_display()").
> 
> Fixes: 2deade5ede56 ("drm/amd/display: Remove hdcp display state with mst fix")
> Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
> ---
>   drivers/gpu/drm/amd/display/modules/hdcp/hdcp_psp.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_psp.c b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_psp.c
> index e58e7b93810b..6b7db8ec9a53 100644
> --- a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_psp.c
> +++ b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_psp.c
> @@ -260,6 +260,9 @@ enum mod_hdcp_status mod_hdcp_hdcp1_create_session(struct mod_hdcp *hdcp)
>   		return MOD_HDCP_STATUS_FAILURE;
>   	}
>   
> +	if (!display)
> +		return MOD_HDCP_STATUS_DISPLAY_NOT_FOUND;
> +
>   	hdcp_cmd = (struct ta_hdcp_shared_memory *)psp->hdcp_context.context.mem_context.shared_buf;
>   
>   	mutex_lock(&psp->hdcp_context.mutex);