FreeBSD Security Advisory – An integer overflow in computing the set of pages containing data to be copied can result in virtual-to-physical address lookups not being performed.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/78265/FreeBSD-SA-09-09.pipe.txt
Source: https://packetstormsecurity.com/files/78265/FreeBSD-Security-Advisory-Pipe-Information-Disclosure.html