The Performance Events subsystem in the Linux kernel before 3.1 does not properly handle event overflows associated with PERF_COUNT_SW_CPU_CLOCK events, which allows local users to cause a denial of service (system hang) via a crafted application.
https://github.com/torvalds/linux/commit/a8b0ca17b80e92faab46ee7179ba9e99ccb61233
https://bugzilla.redhat.com/show_bug.cgi?id=730706
http://www.openwall.com/lists/oss-security/2011/08/16/1