drivers/tty: require read access for controlling terminal
drivers/tty: require read access for controlling terminal

This is mostly a hardening fix, given that write-only access to other
users' ttys is usually only given through setgid tty executables.

Signed-off-by: Jann Horn <1ff1d5ceb421971f93e6626b02a9591b29d7600e@thejh.net>
Cc: 4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@linuxfoundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs