Index: sys/dev/usb/usb_subr.c
===================================================================
RCS file: /cvsroot/src/sys/dev/usb/usb_subr.c,v
retrieving revision 1.217
diff -u -p -r1.217 usb_subr.c
--- sys/dev/usb/usb_subr.c	4 Dec 2016 10:12:35 -0000	1.217
+++ sys/dev/usb/usb_subr.c	14 Dec 2016 16:14:44 -0000
@@ -611,6 +611,16 @@ usbd_set_config_index(struct usbd_device
 		return err;
 	}
 	len = UGETW(cd.wTotalLength);
+	if (len == 0) {
+		printf("%s: bLength		%d\n", __func__, cd.bLength);
+		printf("%s: bDescriptorType	%d\n", __func__, cd.bDescriptorType);
+		printf("%s: bNumInterface	%d\n", __func__, cd.bNumInterface);
+		printf("%s: bConfigurationValue	%d\n", __func__, cd.bConfigurationValue);
+		printf("%s: iConfiguration	%d\n", __func__, cd.iConfiguration);
+		printf("%s: bmAttributes	%d\n", __func__, cd.bmAttributes);
+		printf("%s: bMaxPower		%d\n", __func__, cd.bMaxPower);
+		return USBD_INVAL;
+	}
 	cdp = kmem_alloc(len, KM_SLEEP);
 	if (cdp == NULL)
 		return USBD_NOMEM;