Commit 37480a05 authored Jan 19, 2015 by Peter Hurley Committed by Greg Kroah-Hartman Feb 02, 2015

tty: Prevent untrappable signals from malicious program



Commit 26df6d13 ("tty: Add EXTPROC support for LINEMODE")
allows a process which has opened a pty master to send _any_ signal
to the process group of the pty slave. Although potentially
exploitable by a malicious program running a setuid program on
a pty slave, it's unknown if this exploit currently exists.

Limit to signals actually used.

Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Howard Chu <hyc@symas.com>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: <stable@vger.kernel.org> # 2.6.36+
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 19e3ae6b

drivers/tty/pty.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -210,6 +210,9 @@ static int pty_signal(struct tty_struct *tty, int sig)
		{
		struct pid *pgrp;

		if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP)
		return -EINVAL;

		if (tty->link) {
		pgrp = tty_get_pgrp(tty->link);
		if (pgrp)