[patch 026/108] char: moxa, prevent opening unavailable ports

[Greg KH]

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

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

From: Dirk Eibach <eibach@xxxxxxxx>

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@xxxxxxxxxxxxxxxxxxxx: avoid multiple returns]
Signed-off-by: Dirk Eibach <eibach@xxxxxxxx>
Signed-off-by: Jiri Slaby <jirislaby@xxxxxxxxx>
Cc: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

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

--- a/drivers/char/moxa.c
+++ b/drivers/char/moxa.c
@@ -1184,6 +1184,11 @@ 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;
@@ -1208,8 +1213,8 @@ static int moxa_open(struct tty_struct *
 				moxa_close_port(tty);
 	} else
 		ch->port.flags |= ASYNC_NORMAL_ACTIVE;
+out_unlock:
 	mutex_unlock(&moxa_openlock);
-
 	return retval;
 }
 


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