The IOUSBControllerUserClient::ReadRegister function in the IOUSB controller in IOUSBFamily in Apple OS X before 10.10.2 allows local users to read data from arbitrary kernel-memory locations by leveraging root access and providing a crafted first argument.
https://exchange.xforce.ibmcloud.com/vulnerabilities/100514
http://www.securitytracker.com/id/1031650
http://support.apple.com/HT204244
http://lists.apple.com/archives/security-announce/2015/Jan/msg00003.html