Integer overflow in the hrtimer_forward function (hrtimer.c) in Linux kernel 2.6.21-rc4, when running on 64-bit systems, allows local users to cause a denial of service (infinite loop) via a timer with a large expiry value, which causes the timer to always be expired.

More... (http://nvd.nist.gov/nvd.cfm?cvename=CVE-2007-6712)