From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759665AbZFIT1y (ORCPT ); Tue, 9 Jun 2009 15:27:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753891AbZFIT1q (ORCPT ); Tue, 9 Jun 2009 15:27:46 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:54188 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753883AbZFIT1p (ORCPT ); Tue, 9 Jun 2009 15:27:45 -0400 Date: Tue, 9 Jun 2009 12:27:35 -0700 From: Andrew Morton To: Jiri Slaby Cc: alan@lxorguk.ukuu.org.uk, linux-kernel@vger.kernel.org, jirislaby@gmail.com, eibach@gdsys.de Subject: Re: [PATCH 1/1] Char: moxa, prevent opening unavailable ports Message-Id: <20090609122735.9a915cbf.akpm@linux-foundation.org> In-Reply-To: <1244557981-9443-1-git-send-email-jirislaby@gmail.com> References: <1244557981-9443-1-git-send-email-jirislaby@gmail.com> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 9 Jun 2009 16:33:01 +0200 Jiri Slaby wrote: > From: Dirk Eibach > > 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 > Signed-off-by: Jiri Slaby > --- > 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; Looks good to me. But please, let's avoid adding the multiple-return-statement hand grenade? --- a/drivers/char/moxa.c~char-moxa-prevent-opening-unavailable-ports +++ a/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; } _ btw, what's this code in moxa_open() doing? if (port == MAX_PORTS) { return capable(CAP_SYS_ADMIN) ? 0 : -EPERM; } why does it return 0 if CAP_SYS_ADMIN?