NetBSD 2.0 before 2.0.4, 2.1 before 2.1.1, and 3, when the kernel is compiled with "options DIAGNOSTIC," allows local users to cause a denial of service (kernel assertion panic) via a negative linger time in the SO_LINGER socket option.
http://www.securityfocus.com/bid/15289
http://mail-index.netbsd.org/source-changes/2005/10/21/0038.html
http://mail-index.netbsd.org/netbsd-announce/2005/11/08/0010.html
http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/kern/uipc_socket.c.diff?r1=1.111&r2=1.112