[PATCH 2/2] USB: serial: opticon: stop all I/O on close()

[Johan Hovold <johan@kernel.org>]

Make sure to stop any submitted write URBs on close(). This specifically
avoids a NULL-pointer dereference or use-after-free in case of a late
completion event after driver unbind.

Fixes: 648d4e16567e ("USB: serial: opticon: add write support")
Cc: stable <stable@vger.kernel.org>	# 2.6.30: xxx: USB: serial: opticon: add chars_in_buffer() implementation
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/opticon.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/usb/serial/opticon.c b/drivers/usb/serial/opticon.c
index f7bccf14a71f..61ce359221ec 100644
--- a/drivers/usb/serial/opticon.c
+++ b/drivers/usb/serial/opticon.c
@@ -42,6 +42,8 @@ struct opticon_private {
 	bool cts;
 	int outstanding_urbs;
 	int outstanding_bytes;
+
+	struct usb_anchor anchor;
 };
 
 
@@ -150,6 +152,15 @@ static int opticon_open(struct tty_struct *tty, struct usb_serial_port *port)
 	return res;
 }
 
+static void opticon_close(struct usb_serial_port *port)
+{
+	struct opticon_private *priv = usb_get_serial_port_data(port);
+
+	usb_kill_anchored_urbs(&priv->anchor);
+
+	usb_serial_generic_close(port);
+}
+
 static void opticon_write_control_callback(struct urb *urb)
 {
 	struct usb_serial_port *port = urb->context;
@@ -226,10 +237,13 @@ static int opticon_write(struct tty_struct *tty, struct usb_serial_port *port,
 		(unsigned char *)dr, buffer, count,
 		opticon_write_control_callback, port);
 
+	usb_anchor_urb(urb, priv->anchor);
+
 	/* send it down the pipe */
 	ret = usb_submit_urb(urb, GFP_ATOMIC);
 	if (ret) {
 		dev_err(&port->dev, "failed to submit write urb: %d\n", ret);
+		usb_unanchor_urb(urb);
 		goto error;
 	}
 
@@ -364,6 +378,7 @@ static int opticon_port_probe(struct usb_serial_port *port)
 		return -ENOMEM;
 
 	spin_lock_init(&priv->lock);
+	init_usb_anchor(&priv->anchor);
 
 	usb_set_serial_port_data(port, priv);
 
@@ -391,6 +406,7 @@ static struct usb_serial_driver opticon_device = {
 	.port_probe =		opticon_port_probe,
 	.port_remove =		opticon_port_remove,
 	.open =			opticon_open,
+	.close =		opticon_close,
 	.write =		opticon_write,
 	.write_room = 		opticon_write_room,
 	.chars_in_buffer =	opticon_chars_in_buffer,
-- 
2.24.1