Comment 5 for bug 237306

SRU justification:

Impact: ISDN networking does not work at all because ipppX interfaces
cannot be configured - c.f.
http://bugzilla.kernel.org/show_bug.cgi?id=9923

The patch attached is straight forward 1 line change in the form of an
upstream cherry pick of commit d2dcba612b357a4687843ad4f46629d219233fd7
to not validate the ISDN net device address prior to interface-up by
nullifying the pointer validate_addr.

Testcase: Without the patch, ISDN ipppX interfaces cannot be configured
and ISDN does not work. With the patch, ISDN now works.

Tested by user:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/237306/comments/4