--- /dev/null
+From 403dff4e2c94f275e24fd85f40b2732ffec268a1 Mon Sep 17 00:00:00 2001
+From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Date: Fri, 7 Nov 2014 08:48:15 -0800
+Subject: USB: cdc-acm: check for valid interfaces
+
+From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+commit 403dff4e2c94f275e24fd85f40b2732ffec268a1 upstream.
+
+We need to check that we have both a valid data and control inteface for both
+types of headers (union and not union.)
+
+References: https://bugzilla.kernel.org/show_bug.cgi?id=83551
+Reported-by: Simon Schubert <2+kernel@0x2c.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/usb/class/cdc-acm.c | 9 +++++----
+ 1 file changed, 5 insertions(+), 4 deletions(-)
+
+--- a/drivers/usb/class/cdc-acm.c
++++ b/drivers/usb/class/cdc-acm.c
+@@ -1087,10 +1087,11 @@ next_desc:
+ } else {
+ control_interface = usb_ifnum_to_if(usb_dev, union_header->bMasterInterface0);
+ data_interface = usb_ifnum_to_if(usb_dev, (data_interface_num = union_header->bSlaveInterface0));
+- if (!control_interface || !data_interface) {
+- dev_dbg(&intf->dev, "no interfaces\n");
+- return -ENODEV;
+- }
++ }
++
++ if (!control_interface || !data_interface) {
++ dev_dbg(&intf->dev, "no interfaces\n");
++ return -ENODEV;
+ }
+
+ if (data_interface_num != call_interface_num)