diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index eb2fa8f..343d7d5 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1809,7 +1809,7 @@
 	}
 
 	num_ports = HCS_MAX_PORTS(xhci->hcs_params1);
-	for (i = 0; i < num_ports; i++) {
+	for (i = 0; i < num_ports && xhci->rh_bw; i++) {
 		struct xhci_interval_bw_table *bwt = &xhci->rh_bw[i].bw_table;
 		for (j = 0; j < XHCI_MAX_INTERVAL; j++) {
 			struct list_head *ep = &bwt->interval_bw[j].endpoints;