drm/amd/display: prevent null pointer access

Prevent null pointer access when checking odm tree.
Signed-off-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: <stable@vger.kernel.org>

drivers/gpu/drm/amd/display/dc/dcn30/dcn30_resource.c

@@ -2120,12 +2120,12 @@ static bool dcn30_internal_validate_bw(
 
 		if (split[i]) {
 			if (odm) {
-				if (split[i] == 4 && old_pipe->next_odm_pipe->next_odm_pipe)
+				if (split[i] == 4 && old_pipe->next_odm_pipe && old_pipe->next_odm_pipe->next_odm_pipe)
 					old_index = old_pipe->next_odm_pipe->next_odm_pipe->pipe_idx;
 				else if (old_pipe->next_odm_pipe)
 					old_index = old_pipe->next_odm_pipe->pipe_idx;
 			} else {
-				if (split[i] == 4 && old_pipe->bottom_pipe->bottom_pipe &&
+				if (split[i] == 4 && old_pipe->bottom_pipe && old_pipe->bottom_pipe->bottom_pipe &&
 						old_pipe->bottom_pipe->bottom_pipe->plane_state == old_pipe->plane_state)
 					old_index = old_pipe->bottom_pipe->bottom_pipe->pipe_idx;
 				else if (old_pipe->bottom_pipe &&
@@ -2165,9 +2165,11 @@ static bool dcn30_internal_validate_bw(
 				goto validate_fail;
 			newly_split[pipe_4to1->pipe_idx] = true;
 
-			if (odm && old_pipe->next_odm_pipe->next_odm_pipe->next_odm_pipe)
+			if (odm && old_pipe->next_odm_pipe && old_pipe->next_odm_pipe->next_odm_pipe
+					&& old_pipe->next_odm_pipe->next_odm_pipe->next_odm_pipe)
 				old_index = old_pipe->next_odm_pipe->next_odm_pipe->next_odm_pipe->pipe_idx;
-			else if (!odm && old_pipe->bottom_pipe->bottom_pipe->bottom_pipe &&
+			else if (!odm && old_pipe->bottom_pipe && old_pipe->bottom_pipe->bottom_pipe &&
+					old_pipe->bottom_pipe->bottom_pipe->bottom_pipe &&
 					old_pipe->bottom_pipe->bottom_pipe->bottom_pipe->plane_state == old_pipe->plane_state)
 				old_index = old_pipe->bottom_pipe->bottom_pipe->bottom_pipe->pipe_idx;
 			else