From b2ca699076573c94fee9a73cb0d8645383b602a0 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Wed, 13 Feb 2013 17:53:28 +0100 Subject: USB: serial: fix null-pointer dereferences on disconnect Make sure serial-driver dtr_rts is called with disc_mutex held after checking the disconnected flag. Due to a bug in the tty layer, dtr_rts may get called after a device has been disconnected and the tty-device unregistered. Some drivers have had individual checks for disconnect to make sure the disconnected interface was not accessed, but this should really be handled in usb-serial core (at least until the long-standing tty-bug has been fixed). Note that the problem has been made more acute with commit 0998d0631001 ("device-core: Ensure drvdata = NULL when no driver is bound") as the port data is now also NULL when dtr_rts is called resulting in further oopses. Reported-by: Chris Ruehl Cc: stable Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman --- drivers/usb/serial/mct_u232.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) (limited to 'drivers/usb/serial/mct_u232.c') diff --git a/drivers/usb/serial/mct_u232.c b/drivers/usb/serial/mct_u232.c index b6911757c855..d9c86516fed4 100644 --- a/drivers/usb/serial/mct_u232.c +++ b/drivers/usb/serial/mct_u232.c @@ -499,19 +499,15 @@ static void mct_u232_dtr_rts(struct usb_serial_port *port, int on) unsigned int control_state; struct mct_u232_private *priv = usb_get_serial_port_data(port); - mutex_lock(&port->serial->disc_mutex); - if (!port->serial->disconnected) { - /* drop DTR and RTS */ - spin_lock_irq(&priv->lock); - if (on) - priv->control_state |= TIOCM_DTR | TIOCM_RTS; - else - priv->control_state &= ~(TIOCM_DTR | TIOCM_RTS); - control_state = priv->control_state; - spin_unlock_irq(&priv->lock); - mct_u232_set_modem_ctrl(port, control_state); - } - mutex_unlock(&port->serial->disc_mutex); + spin_lock_irq(&priv->lock); + if (on) + priv->control_state |= TIOCM_DTR | TIOCM_RTS; + else + priv->control_state &= ~(TIOCM_DTR | TIOCM_RTS); + control_state = priv->control_state; + spin_unlock_irq(&priv->lock); + + mct_u232_set_modem_ctrl(port, control_state); } static void mct_u232_close(struct usb_serial_port *port) -- cgit v1.2.3