4.14-stable review patch. If anyone has any objections, please let me know.
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From: Johan Hovold johan@kernel.org
commit 8bcd4e6a8decac251d55c4377e2e67f052777ce0 upstream.
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: bed35c6dfa6a ("serdev: add a tty port controller driver") Signed-off-by: Johan Hovold johan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/tty/serdev/serdev-ttyport.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
--- a/drivers/tty/serdev/serdev-ttyport.c +++ b/drivers/tty/serdev/serdev-ttyport.c @@ -57,12 +57,19 @@ static void ttyport_write_wakeup(struct { struct serdev_controller *ctrl = port->client_data; struct serport *serport = serdev_controller_get_drvdata(ctrl); + struct tty_struct *tty;
- if (test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &port->tty->flags) && + tty = tty_port_tty_get(port); + if (!tty) + return; + + 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 = {