[PATCH 1/2] USB: serial: console: fix use-after-free on disconnect

[Johan Hovold <johan@kernel.org>]

A clean-up patch removing removing two redundant NULL-checks from the
console disconnect handler inadvertently also removed a third check.
This could lead to the struct usb_serial being prematurely freed by the
console code when a driver accepts but does not register any ports for
an interface which also lacks endpoint descriptors.

Fixes: 0e517c93dc02 ("USB: serial: console: clean up sanity checks")
Cc: stable <stable@vger.kernel.org>     # 4.11
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/console.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/serial/console.c b/drivers/usb/serial/console.c
index fdf89800ebc3..ed8ba3ef5c79 100644
--- a/drivers/usb/serial/console.c
+++ b/drivers/usb/serial/console.c
@@ -265,7 +265,7 @@ static struct console usbcons = {
 
 void usb_serial_console_disconnect(struct usb_serial *serial)
 {
-	if (serial->port[0] == usbcons_info.port) {
+	if (serial->port[0] && serial->port[0] == usbcons_info.port) {
 		usb_serial_console_exit();
 		usb_serial_put(serial);
 	}
-- 
2.14.2