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Commit 8bcd4e6a authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
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serdev: ttyport: fix NULL-deref on hangup 



Make sure to use a properly refcounted tty_struct in write_wake up to
avoid dereferencing a NULL-pointer when a port is being hung up.

Fixes: bed35c6d ("serdev: add a tty port controller driver")
Cc: stable <stable@vger.kernel.org>     # 4.11
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent fd00cf81

drivers/tty/serdev/serdev-ttyport.c

+9 −2
Original line number Diff line number Diff line
@@ -49,12 +49,19 @@ static void ttyport_write_wakeup(struct tty_port *port) 
{

	struct serdev_controller *ctrl = port->client_data;

	struct serport *serport = serdev_controller_get_drvdata(ctrl);

	struct tty_struct *tty;



	tty = tty_port_tty_get(port);

	if (!tty)

		return;



	if (test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &port->tty->flags) &&

	if (test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags) &&

	    test_bit(SERPORT_ACTIVE, &serport->flags))

		serdev_controller_write_wakeup(ctrl);



	wake_up_interruptible_poll(&port->tty->write_wait, POLLOUT);

	wake_up_interruptible_poll(&tty->write_wait, POLLOUT);



	tty_kref_put(tty);

}



static const struct tty_port_client_operations client_ops = {