The shmat system call in the System V Shared Memory interface for FreeBSD 5.2 and earlier, NetBSD 1.3 and earlier, and OpenBSD 2.6 and earlier, does not properly decrement a shared memory segment's reference count when the vm_map_find function fails, which could allow local users to gain read or write access to a portion of kernel memory and gain privileges.
https://exchange.xforce.ibmcloud.com/vulnerabilities/15061
http://www.securityfocus.com/bid/9586
http://www.pine.nl/press/pine-cert-20040201.txt