diff --git a/sys/dev/drm/radeon/radeon_dp_mst.c b/sys/dev/drm/radeon/radeon_dp_mst.c
--- a/sys/dev/drm/radeon/radeon_dp_mst.c
+++ b/sys/dev/drm/radeon/radeon_dp_mst.c
@@ -135,6 +135,8 @@
 		if (!mst_enc->enc_active)
 			continue;
 
+		if (idx >= 6)
+			break;
 		new_attribs[idx].fe = mst_enc->fe;
 		new_attribs[idx].slots = drm_dp_mst_get_vcpi_slots(&mst_conn->mst_mgr, mst_enc->port);
 		idx++;