The __group_complete_signal function in the RCU signal handling (signal.c) in Linux kernel 2.6.16, and possibly other versions, has unknown impact and attack vectors related to improper use of BUG_ON.
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=188604
http://www.vupen.com/english/advisories/2006/2554
http://www.securityfocus.com/bid/17640
http://www.novell.com/linux/security/advisories/2006-05-31.html
http://www.debian.org/security/2006/dsa-1103
http://secunia.com/advisories/20914