[PATCH 4.9 60/97] USB: serial: ch341: handle unbound port at reset_resume

[Greg Kroah-Hartman]

From: Johan Hovold <johan@xxxxxxxxxx>

commit 4d5ef53f75c22d28f490bcc5c771fcc610a9afa4 upstream.

Check for NULL port data in reset_resume() to avoid dereferencing a NULL
pointer in case the port device isn't bound to a driver (e.g. after a
failed control request at port probe).

Fixes: 1ded7ea47b88 ("USB: ch341 serial: fix port number changed after resume")
Cc: stable <stable@xxxxxxxxxxxxxxx>     # 2.6.30
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/ch341.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -555,9 +555,13 @@ static int ch341_tiocmget(struct tty_str
 static int ch341_reset_resume(struct usb_serial *serial)
 {
 	struct usb_serial_port *port = serial->port[0];
-	struct ch341_private *priv = usb_get_serial_port_data(port);
+	struct ch341_private *priv;
 	int ret;
 
+	priv = usb_get_serial_port_data(port);
+	if (!priv)
+		return 0;
+
 	/* reconfigure ch341 serial port after bus-reset */
 	ch341_configure(serial->dev, priv);