moxa: prevent opening unavailable ports

In moxa.c there are 32 minor numbers reserved for each device. The
number of ports actually available per device is stored in
moxa_board_conf->numPorts. This number is not considered in moxa_open().
Opening a port that is not available results in a kernel oops.
This patch adds a test to moxa_open() that prevents opening unavailable
ports.

Signed-off-by: Dirk Eibach <eibach@gdsys.de>
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/char/moxa.c b/drivers/char/moxa.c
index 4a4cab73d0be176aa640c9717bc7582231b39495..65b6ff2442c6df4edfd839b37752ded8340df9c9 100644 (file)
--- a/drivers/char/moxa.c
+++ b/drivers/char/moxa.c
@@ -1184,6 +1184,11 @@ static int moxa_open(struct tty_struct *tty, struct file *filp)
                return -ENODEV;
        }
 
+       if (port % MAX_PORTS_PER_BOARD >= brd->numPorts) {
+               mutex_unlock(&moxa_openlock);
+               return -ENODEV;
+       }
+
        ch = &brd->ports[port % MAX_PORTS_PER_BOARD];
        ch->port.count++;
        tty->driver_data = ch;