*BSD procfs vulnerability

From the archives at Security Focus, In January 1997 a fatal flaw in *BSD procfs code (leading to a local root compromise) was discussed on various security forums. The exploit code dealt with /proc/pid/mem interface. Since then *BSD kernels contained a simple fix which was meant to close this hole. Unfortunately, throughout these three years it was still possible to abuse /proc/pid/mem in a similar, though more complicated fashion, which could lead to local root compromise." Patches are included.