Pull driver core fixes from Greg KH:
"Here are two driver core (well, sysfs) fixes for 3.15-rc6 that resolve
some reported issues and a regression from 3.13"
* tag 'driver-core-3.15-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
sysfs: make sure read buffer is zeroed
kernfs, sysfs, cgroup: restrict extra perm check on open to sysfs