The kernel in Apple iOS before 7 does not initialize unspecified kernel data structures, which allows local users to obtain sensitive information from kernel stack memory via the (1) msgctl API or (2) segctl API.
http://www.securitytracker.com/id/1029054
http://support.apple.com/kb/HT5934
http://lists.apple.com/archives/security-announce/2013/Sep/msg00006.html
http://lists.apple.com/archives/security-announce/2013/Oct/msg00004.html