USB: pl2303: fix device initialisation at open

commit 2d8f4447 upstream.

Do not use uninitialised termios data to determine when to configure the
device at open.

This also prevents stack data from leaking to userspace in the OOM error
path.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
[bwh: Backported to 3.2: tty_struct::termios is a pointer, not a struct]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/pl2303.c

@@ -269,7 +269,7 @@ static void pl2303_set_termios(struct tty_struct *tty,
 	   serial settings even to the same values as before. Thus
 	   we actually need to filter in this specific case */
 
-	if (!tty_termios_hw_change(tty->termios, old_termios))
+	if (old_termios && !tty_termios_hw_change(tty->termios, old_termios))
 		return;
 
 	cflag = tty->termios->c_cflag;
@@ -278,7 +278,8 @@ static void pl2303_set_termios(struct tty_struct *tty,
 	if (!buf) {
 		dev_err(&port->dev, "%s - out of memory.\n", __func__);
 		/* Report back no change occurred */
-		*tty->termios = *old_termios;
+		if (old_termios)
+			*tty->termios = *old_termios;
 		return;
 	}
 
@@ -416,7 +417,7 @@ static void pl2303_set_termios(struct tty_struct *tty,
 	control = priv->line_control;
 	if ((cflag & CBAUD) == B0)
 		priv->line_control &= ~(CONTROL_DTR | CONTROL_RTS);
-	else if ((old_termios->c_cflag & CBAUD) == B0)
+	else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
 		priv->line_control |= (CONTROL_DTR | CONTROL_RTS);
 	if (control != priv->line_control) {
 		control = priv->line_control;
@@ -477,7 +478,6 @@ static void pl2303_close(struct usb_serial_port *port)
 
 static int pl2303_open(struct tty_struct *tty, struct usb_serial_port *port)
 {
-	struct ktermios tmp_termios;
 	struct usb_serial *serial = port->serial;
 	struct pl2303_private *priv = usb_get_serial_port_data(port);
 	int result;
@@ -495,7 +495,7 @@ static int pl2303_open(struct tty_struct *tty, struct usb_serial_port *port)
 
 	/* Setup termios */
 	if (tty)
-		pl2303_set_termios(tty, port, &tmp_termios);
+		pl2303_set_termios(tty, port, NULL);
 
 	dbg("%s - submitting interrupt urb", __func__);
 	result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);