Integer signedness error in the DCCP support in the do_dccp_getsockopt function in net/dccp/proto.c in Linux kernel 2.6.20 and later allows local users to read kernel memory or cause a denial of service (oops) via a negative optlen value.
https://exchange.xforce.ibmcloud.com/vulnerabilities/33274
http://www.vupen.com/english/advisories/2007/1143
http://www.ubuntu.com/usn/usn-464-1
http://www.securitytracker.com/id?1017820
http://www.securityfocus.com/bid/23162
http://www.securityfocus.com/archive/1/464144/100/0/threaded
http://www.securityfocus.com/archive/1/463934/100/0/threaded
http://securityreason.com/securityalert/2482