MFC r330356 (eadler): sys/linux: Fix a few potential infoleaks in Linux IPC
admbugs: 765, 812, 813, 814
Submitted by: Domagoj Stolfa <domagoj.stolfa@gmail.com>
Reported by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Reported by: Vlad Tsyrklevich