cryptodev-linux <= 1.14 get_userbuf Use After Free LPE

cryptodev-linux version 1.14 and prior contain a page reference handling flaw in the get_userbuf function of the /dev/crypto device driver that allows local users to trigger use-after-free conditions. Attackers with access to the /dev/crypto interface can repeatedly decrement reference counts of controlled pages to achieve local privilege escalation.