[patch 04/30] char: moxa, prevent opening unavailable ports

[Greg KH <gregkh@suse.de>]

[-- Attachment #1: char-moxa-prevent-opening-unavailable-ports.patch --]
[-- Type: text/plain, Size: 1531 bytes --]

2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Dirk Eibach <eibach@gdsys.de>

commit a90b037583d5f1ae3e54e9c687c79df82d1d34a4 upstream.

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.

[akpm@linux-foundation.org: avoid multiple returns]
Signed-off-by: Dirk Eibach <eibach@gdsys.de>
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/char/moxa.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/char/moxa.c
+++ b/drivers/char/moxa.c
@@ -1158,6 +1158,11 @@ static int moxa_open(struct tty_struct *
 		return -ENODEV;
 	}
 
+	if (port % MAX_PORTS_PER_BOARD >= brd->numPorts) {
+		retval = -ENODEV;
+		goto out_unlock;
+	}
+
 	ch = &brd->ports[port % MAX_PORTS_PER_BOARD];
 	ch->port.count++;
 	tty->driver_data = ch;
@@ -1182,8 +1187,8 @@ static int moxa_open(struct tty_struct *
 				moxa_close_port(ch);
 	} else
 		ch->port.flags |= ASYNC_NORMAL_ACTIVE;
+out_unlock:
 	mutex_unlock(&moxa_openlock);
-
 	return retval;
 }