FreeBSD 4.5 and earlier, and possibly other BSD-based operating systems, allows local users to write to or read from restricted files by closing the file descriptors 0 (standard input), 1 (standard output), or 2 (standard error), which may then be re

FreeBSD kernel 4.6 and earlier closes the file descriptors 0, 1, and 2 after they have already been assigned to /dev/null when the descriptors reference procfs or linprocfs, which could allow local users to reuse the file descriptors in a setuid or s