USB: serial: console: fix use-after-free after failed setup

Make sure to reset the USB-console port pointer when console setup fails
in order to avoid having the struct usb_serial be prematurely freed by
the console code when the device is later disconnected.

Fixes: 73e487f ("[PATCH] USB console: fix disconnection issues")
Cc: stable <[email protected]>	# 2.6.18
Acked-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Johan Hovold <[email protected]>
(cherry picked from commit 299d757)

Orabug: 27206824
CVE: CVE-2017-16525

This bug is partly caused by a clean-up patch that is not merged in uek4,
so it only needs 1 commit to fix it.

Signed-off-by: Tim Tianyang Chen <[email protected]>
Reviewed-by: Reviewed-by: Jack Vogel <[email protected]>

Author: jhovold

drivers/usb/serial/console.c

@@ -189,6 +189,7 @@ static int usb_console_setup(struct console *co, char *options)
 	tty_kref_put(tty);
  reset_open_count:
 	port->port.count = 0;
+	info->port = NULL;
 	usb_autopm_put_interface(serial->interface);
  error_get_interface:
 	usb_serial_put(serial);