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 <chris.ruehl@gtsys.com.hk>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 90ceef1..d07fccf 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1886,24 +1886,22 @@
{
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);
}
/*