Ubuntu Linux 6.10 for the PowerPC (PPC) allows local users to cause a denial of service (resource consumption) by using the (1) sys_get_robust_list and (2) sys_set_robust_list functions to create processes that cannot be killed.
http://www.ubuntu.com/usn/usn-395-1
http://www.securityfocus.com/bid/21582
http://www.novell.com/linux/security/advisories/2006_79_kernel.html
http://secunia.com/advisories/23474