[PATCH 01/11] drm/amd/display: add null check

[Ray Wu <ray.wu@amd.com>]

From: Peichen Huang <PeiChen.Huang@amd.com>

[WHY]
Prevents null pointer dereferences to enhance function robustness

[HOW]
Adds early null check and return false if invalid.

Reviewed-by: Cruise Hung <cruise.hung@amd.com>
Signed-off-by: Peichen Huang <PeiChen.Huang@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
---
 drivers/gpu/drm/amd/display/dc/core/dc.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
index 0146ad4e23c8..c744aa9d830f 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -6398,11 +6398,13 @@ unsigned int dc_get_det_buffer_size_from_state(const struct dc_state *context)
  */
 bool dc_get_host_router_index(const struct dc_link *link, unsigned int *host_router_index)
 {
-	struct dc *dc = link->ctx->dc;
+	struct dc *dc;
 
-	if (link->ep_type != DISPLAY_ENDPOINT_USB4_DPIA)
+	if (!link || !host_router_index || link->ep_type != DISPLAY_ENDPOINT_USB4_DPIA)
 		return false;
 
+	dc = link->ctx->dc;
+
 	if (link->link_index < dc->lowest_dpia_link_index)
 		return false;
 
-- 
2.43.0