diff --git a/drivers/isdn/hardware/mISDN/hfcsusb.c b/drivers/isdn/hardware/mISDN/hfcsusb.c
index 6d05946b445eb039aeb6c9c755e94dbe8b8f1dac..060dc7fd66c1d5eed4cefc5fbceb0bcf3e6f6358 100644
--- a/drivers/isdn/hardware/mISDN/hfcsusb.c
+++ b/drivers/isdn/hardware/mISDN/hfcsusb.c
@@ -1967,6 +1967,9 @@ hfcsusb_probe(struct usb_interface *intf, const struct usb_device_id *id)
 
 				/* get endpoint base */
 				idx = ((ep_addr & 0x7f) - 1) * 2;
+				if (idx > 15)
+					return -EIO;
+
 				if (ep_addr & 0x80)
 					idx++;
 				attr = ep->desc.bmAttributes;