[ 017/150] USB: serial: fix null-pointer dereferences on disconnect

Greg Kroah-Hartman
2013-02-27T01:19:20Z

From: Johan Hovold <jhovold@gmail.com>

commit b2ca699076573c94fee9a73cb0d8645383b602a0 upstream.

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 <chris.ruehl@gtsys.com.hk>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/serial/ftdi_sio.c | 20 +++++++++-----------
drivers/usb/serial/mct_u232.c | 22 +++++++++-------------
drivers/usb/serial/quatech2.c | 18 ++++++++----------
drivers/usb/serial/sierra.c | 8 +-------
drivers/usb/serial/ssu100.c | 19 ++++++++-----------
drivers/usb/serial/usb-serial.c | 14 ++++++++++++--
drivers/usb/serial/usb_wwan.c | 8 +++-----
7 files changed, 50 insertions(+), 59 deletions(-)

--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1886,24 +1886,22 @@ static void ftdi_dtr_rts(struct usb_seri
{
struct ftdi_private *priv = usb_get_serial_port_data(port);

- mutex_lock(&port->serial->disc_mutex);
- if (!port->serial->disconnected) {
- /* Disable flow control */
- if (!on && usb_control_msg(port->serial->dev,
+ /* Disable flow control */
+ if (!on) {
+ if (usb_control_msg(port->serial->dev,
usb_sndctrlpipe(port->serial->dev, 0),
FTDI_SIO_SET_FLOW_CTRL_REQUEST,
FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,
0, priv->interface, NULL, 0,
WDR_TIMEOUT) < 0) {
- dev_err(&port->dev, "error from flowcontrol urb\n");
+ dev_err(&port->dev, "error from flowcontrol urb\n");
}
- /* drop RTS and DTR */
- if (on)
- set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
- else
- clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
}
- mutex_unlock(&port->serial->disc_mutex);
+ /* drop RTS and DTR */
+ if (on)
+ set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
+ else
+ clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
}

/*
--- 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_
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)
--- a/drivers/usb/serial/quatech2.c
+++ b/drivers/usb/serial/quatech2.c
@@ -945,19 +945,17 @@ static void qt2_dtr_rts(struct usb_seria
struct usb_device *dev = port->serial->dev;
struct qt2_port_private *port_priv = usb_get_serial_port_data(port);

- mutex_lock(&port->serial->disc_mutex);
- if (!port->serial->disconnected) {
- /* Disable flow control */
- if (!on && qt2_setregister(dev, port_priv->device_port,
+ /* Disable flow control */
+ if (!on) {
+ if (qt2_setregister(dev, port_priv->device_port,
UART_MCR, 0) < 0)
dev_warn(&port->dev, "error from flowcontrol urb\n");
- /* drop RTS and DTR */
- if (on)
- update_mctrl(port_priv, TIOCM_DTR | TIOCM_RTS, 0);
- else
- update_mctrl(port_priv, 0, TIOCM_DTR | TIOCM_RTS);
}
- mutex_unlock(&port->serial->disc_mutex);
+ /* drop RTS and DTR */
+ if (on)
+ update_mctrl(port_priv, TIOCM_DTR | TIOCM_RTS, 0);
+ else
+ update_mctrl(port_priv, 0, TIOCM_DTR | TIOCM_RTS);
}

static void qt2_update_msr(struct usb_serial_port *port, unsigned char *ch)
--- a/drivers/usb/serial/sierra.c
+++ b/drivers/usb/serial/sierra.c
@@ -861,19 +861,13 @@ static int sierra_open(struct tty_struct

static void sierra_dtr_rts(struct usb_serial_port *port, int on)
{
- struct usb_serial *serial = port->serial;
struct sierra_port_private *portdata;

portdata = usb_get_serial_port_data(port);
portdata->rts_state = on;
portdata->dtr_state = on;

- if (serial->dev) {
- mutex_lock(&serial->disc_mutex);
- if (!serial->disconnected)
- sierra_send_setup(port);
- mutex_unlock(&serial->disc_mutex);
- }
+ sierra_send_setup(port);
}

static int sierra_startup(struct usb_serial *serial)
--- a/drivers/usb/serial/ssu100.c
+++ b/drivers/usb/serial/ssu100.c
@@ -506,19 +506,16 @@ static void ssu100_dtr_rts(struct usb_se
{
struct usb_device *dev = port->serial->dev;

- mutex_lock(&port->serial->disc_mutex);
- if (!port->serial->disconnected) {
- /* Disable flow control */
- if (!on &&
- ssu100_setregister(dev, 0, UART_MCR, 0) < 0)
+ /* Disable flow control */
+ if (!on) {
+ if (ssu100_setregister(dev, 0, UART_MCR, 0) < 0)
dev_err(&port->dev, "error from flowcontrol urb\n");
- /* drop RTS and DTR */
- if (on)
- set_mctrl(dev, TIOCM_DTR | TIOCM_RTS);
- else
- clear_mctrl(dev, TIOCM_DTR | TIOCM_RTS);
}
- mutex_unlock(&port->serial->disc_mutex);
+ /* drop RTS and DTR */
+ if (on)
+ set_mctrl(dev, TIOCM_DTR | TIOCM_RTS);
+ else
+ clear_mctrl(dev, TIOCM_DTR | TIOCM_RTS);
}

static void ssu100_update_msr(struct usb_serial_port *port, u8 msr)
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -688,10 +688,20 @@ static int serial_carrier_raised(struct
static void serial_dtr_rts(struct tty_port *port, int on)
{
struct usb_serial_port *p = container_of(port, struct usb_serial_port, port);
- struct usb_serial_driver *drv = p->serial->type;
+ struct usb_serial *serial = p->serial;
+ struct usb_serial_driver *drv = serial->type;

- if (drv->dtr_rts)
+ if (!drv->dtr_rts)
+ return;
+ /*
+ * Work-around bug in the tty-layer which can result in dtr_rts
+ * being called after a disconnect (and tty_unregister_device
+ * has returned). Remove once bug has been squashed.
+ */
+ mutex_lock(&serial->disc_mutex);
+ if (!serial->disconnected)
drv->dtr_rts(p, on);
+ mutex_unlock(&serial->disc_mutex);
}

static const struct tty_port_operations serial_port_ops = {
--- a/drivers/usb/serial/usb_wwan.c
+++ b/drivers/usb/serial/usb_wwan.c
@@ -38,7 +38,6 @@

void usb_wwan_dtr_rts(struct usb_serial_port *port, int on)
{
- struct usb_serial *serial = port->serial;
struct usb_wwan_port_private *portdata;
struct usb_wwan_intf_private *intfdata;

@@ -48,12 +47,11 @@ void usb_wwan_dtr_rts(struct usb_serial_
return;

portdata = usb_get_serial_port_data(port);
- mutex_lock(&serial->disc_mutex);
+ /* FIXME: locking */
portdata->rts_state = on;
portdata->dtr_state = on;
- if (serial->dev)
- intfdata->send_setup(port);
- mutex_unlock(&serial->disc_mutex);
+
+ intfdata->send_setup(port);
}
EXPORT_SYMBOL(usb_wwan_dtr_rts);