Integer signedness error in the amd64_set_ldt function in sys/amd64/amd64/sys_machdep.c in FreeBSD 9.3 before p39, 10.1 before p31, and 10.2 before p14 allows local users to cause a denial of service (kernel panic) via an i386_set_ldt system call, which triggers a heap-based buffer overflow.
https://security.FreeBSD.org/advisories/FreeBSD-SA-16:15.sysarch.asc
http://www.securitytracker.com/id/1035309
http://www.securityfocus.com/archive/1/537813/100/0/threaded
http://www.securityfocus.com/archive/1/537812/100/0/threaded
http://www.coresecurity.com/advisories/freebsd-kernel-amd64setldt-heap-overflow