USB: serial/kobil_sct, fix potential tty NULL dereference

Make sure that we check the return value of tty_port_tty_get.
Sometimes it may return NULL and we later dereference that.

The only place here is in kobil_read_int_callback, so fix it.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/serial/kobil_sct.c b/drivers/usb/serial/kobil_sct.c
index bd5bd85..b382d9a 100644 (file)
--- a/drivers/usb/serial/kobil_sct.c
+++ b/drivers/usb/serial/kobil_sct.c
@@ -372,7 +372,7 @@ static void kobil_read_int_callback(struct urb *urb)
        }
 
        tty = tty_port_tty_get(&port->port);
-       if (urb->actual_length) {
+       if (tty && urb->actual_length) {
 
                /* BEGIN DEBUG */
                /*