Commit 6d27a63c authored Jan 10, 2016 by Peter Hurley Committed by Greg Kroah-Hartman Jan 26, 2016

n_tty: Fix unsafe reference to "other" ldisc



Although n_tty_check_unthrottle() has a valid ldisc reference (since
the tty core gets the ldisc ref in tty_read() before calling the line
discipline read() method), it does not have a valid ldisc reference to
the "other" pty of a pty pair. Since getting an ldisc reference for
tty->link essentially open-codes tty_wakeup(), just replace with the
equivalent tty_wakeup().

Cc: <stable@vger.kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 5c17c861

drivers/tty/n_tty.c

+2 −5

Original line number	Diff line number	Diff line
		@@ -269,16 +269,13 @@ static void n_tty_check_throttle(struct tty_struct *tty)

		static void n_tty_check_unthrottle(struct tty_struct *tty)
		{
		if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
		tty->link->ldisc->ops->write_wakeup == n_tty_write_wakeup) {
		if (tty->driver->type == TTY_DRIVER_TYPE_PTY) {
		if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
		return;
		if (!tty->count)
		return;
		n_tty_kick_worker(tty);
		n_tty_write_wakeup(tty->link);
		if (waitqueue_active(&tty->link->write_wait))
		wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
		tty_wakeup(tty->link);
		return;
		}