Commit message: USB: cypress_m8: add endpoint sanity check

An attack using missing endpoints exists.

CVE-2016-3137

Signed-off-by: Oliver Neukum <ONeukum@suse.com>
CC: stable@vger.kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CVE: CVE-2016-3137
CWE: CWE-703
Vulnerability description: drivers/usb/serial/cypress_m8.c in the Linux kernel before 4.5.1 allows physically proximate attackers to cause a denial of service (NULL pointer dereference and system crash) via a USB device without both an interrupt-in and an interrupt-out endpoint descriptor, related to the cypress_generic_port_probe and cypress_open functions.

Project: linux
File: cypress_m8.c

static int cypress_generic_port_probe(struct usb_serial_port *port)
{
 	struct usb_serial *serial = port->serial;
 	struct cypress_private *priv;
 
	if (!port->interrupt_out_urb || !port->interrupt_in_urb) {
		dev_err(&port->dev, "required endpoint is missing\n");
		return -ENODEV;
	}

 	priv = kzalloc(sizeof(struct cypress_private), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;

	priv->comm_is_ok = !0;
	spin_lock_init(&priv->lock);
	if (kfifo_alloc(&priv->write_fifo, CYPRESS_BUF_SIZE, GFP_KERNEL)) {
		kfree(priv);
		return -ENOMEM;
	}

	/* Skip reset for FRWD device. It is a workaound:
	   device hangs if it receives SET_CONFIGURE in Configured
	   state. */
	if (!is_frwd(serial->dev))
		usb_reset_configuration(serial->dev);

	priv->cmd_ctrl = 0;
	priv->line_control = 0;
	priv->termios_initialized = 0;
	priv->rx_flags = 0;
	/* Default packet format setting is determined by packet size.
	   Anything with a size larger then 9 must have a separate
	   count field since the 3 bit count field is otherwise too
	   small.  Otherwise we can use the slightly more compact
	   format.  This is in accordance with the cypress_m8 serial
	   converter app note. */
	if (port->interrupt_out_size > 9)
		priv->pkt_fmt = packet_format_1;
	else
		priv->pkt_fmt = packet_format_2;

	if (interval > 0) {
		priv->write_urb_interval = interval;
		priv->read_urb_interval = interval;
		dev_dbg(&port->dev, "%s - read & write intervals forced to %d\n",
			__func__, interval);
	} else {
		priv->write_urb_interval = port->interrupt_out_urb->interval;
		priv->read_urb_interval = port->interrupt_in_urb->interval;
		dev_dbg(&port->dev, "%s - intervals: read=%d write=%d\n",
			__func__, priv->read_urb_interval,
			priv->write_urb_interval);
	}
	usb_set_serial_port_data(port, priv);

	port->port.drain_delay = 256;

	return 0;
}

Project: linux
File: cypress_m8.c

static int cypress_open(struct tty_struct *tty, struct usb_serial_port *port)
{
	struct cypress_private *priv = usb_get_serial_port_data(port);
	struct usb_serial *serial = port->serial;
	unsigned long flags;
	int result = 0;

	if (!priv->comm_is_ok)
		return -EIO;

	/* clear halts before open */
	usb_clear_halt(serial->dev, 0x81);
	usb_clear_halt(serial->dev, 0x02);

	spin_lock_irqsave(&priv->lock, flags);
	/* reset read/write statistics */
	priv->bytes_in = 0;
	priv->bytes_out = 0;
	priv->cmd_count = 0;
	priv->rx_flags = 0;
	spin_unlock_irqrestore(&priv->lock, flags);

	/* Set termios */
	cypress_send(port);

	if (tty)
 		cypress_set_termios(tty, port, &priv->tmp_termios);
 
 	/* setup the port and start reading from the device */
 	usb_fill_int_urb(port->interrupt_in_urb, serial->dev,
 		usb_rcvintpipe(serial->dev, port->interrupt_in_endpointAddress),
 		port->interrupt_in_urb->transfer_buffer,
		port->interrupt_in_urb->transfer_buffer_length,
		cypress_read_int_callback, port, priv->read_urb_interval);
	result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);

	if (result) {
		dev_err(&port->dev,
			"%s - failed submitting read urb, error %d\n",
							__func__, result);
		cypress_set_dead(port);
	}

	return result;
} /* cypress_open */