--- zzzz-none-000/linux-4.4.60/drivers/usb/class/cdc-acm.c	2017-04-08 07:53:53.000000000 +0000
+++ dragonfly-4020-701/linux-4.4.60/drivers/usb/class/cdc-acm.c	2018-11-08 13:36:17.000000000 +0000
@@ -1146,6 +1146,10 @@
 			elength = 1;
 			goto next_desc;
 		}
+		if ((buflen < elength) || (elength < 3)) {
+			dev_err(&intf->dev, "invalid descriptor buffer length\n");
+			break;
+		}
 		if (buffer[1] != USB_DT_CS_INTERFACE) {
 			dev_err(&intf->dev, "skipping garbage\n");
 			goto next_desc;