The RBAC functionality in grsecurity before 2.1.11-2.6.24.5 and 2.1.11-2.4.36.2 does not enforce user_transition_deny and user_transition_allow rules for the (1) sys_setfsuid and (2) sys_setfsgid calls, which allows local users to bypass restrictions for those calls.
https://exchange.xforce.ibmcloud.com/vulnerabilities/41952
http://www.vupen.com/english/advisories/2008/1323/references
http://www.securitytracker.com/id?1019919
http://www.securityfocus.com/bid/28889