diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index b7114c3..a3ecd8b 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -996,6 +996,12 @@
 	if (!vdev)
 		return;
 
+	if (vdev->real_port == 0 ||
+			vdev->real_port > HCS_MAX_PORTS(xhci->hcs_params1)) {
+		xhci_dbg(xhci, "Bad vdev->real_port.\n");
+		goto out;
+	}
+
 	tt_list_head = &(xhci->rh_bw[vdev->real_port - 1].tts);
 	list_for_each_entry_safe(tt_info, next, tt_list_head, tt_list) {
 		/* is this a hub device that added a tt_info to the tts list */
@@ -1009,6 +1015,7 @@
 			}
 		}
 	}
+out:
 	/* we are now at a leaf device */
 	xhci_free_virt_device(xhci, slot_id);
 }