Integer overflow in the f_count counter in FreeBSD before 4.2 through 5.0 allows local users to cause a denial of service (crash) and possibly execute arbitrary code via multiple calls to (1) fpathconf and (2) lseek, which do not properly decrement f_count through a call to fdrop.
http://www.securitytracker.com/id?1005898
http://www.securityfocus.com/bid/6524
http://www.securityfocus.com/archive/1/305308/30/26420/threaded
http://www.pine.nl/press/pine-cert-20030101.txt
http://www.iss.net/security_center/static/10993.php
http://secunia.com/advisories/7821
http://archives.neohapsis.com/archives/vulnwatch/2003-q1/0006.html
http://archives.neohapsis.com/archives/bugtraq/2003-01/0057.html