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

[Chenyuan Yang]

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 <chenyua...@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);
-- 
2.34.1