[PATCH 4.4 113/132] USB: serial: keyspan_pda: fix tx-unthrottle use-after-free

[Greg Kroah-Hartman]

From: Johan Hovold <johan@xxxxxxxxxx>

commit 49fbb8e37a961396a5b6c82937c70df91de45e9d upstream.

The driver's transmit-unthrottle work was never flushed on disconnect,
something which could lead to the driver port data being freed while the
unthrottle work is still scheduled.

Fix this by cancelling the unthrottle work when shutting down the port.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@xxxxxxxxxxxxxxx
Acked-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/serial/keyspan_pda.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -651,8 +651,12 @@ error:
 }
 static void keyspan_pda_close(struct usb_serial_port *port)
 {
+	struct keyspan_pda_private *priv = usb_get_serial_port_data(port);
+
 	usb_kill_urb(port->write_urb);
 	usb_kill_urb(port->interrupt_in_urb);
+
+	cancel_work_sync(&priv->unthrottle_work);
 }