[PATCH 1/1] Char: moxa, prevent opening unavailable ports

[Jiri Slaby <jirislaby@gmail.com>]

From: Dirk Eibach <eibach@gdsys.de>

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>
---
 drivers/char/moxa.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/char/moxa.c b/drivers/char/moxa.c
index 4a4cab7..65b6ff2 100644
--- 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;
-- 
1.6.3.2