Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756000AbZJGWlo (ORCPT ); Wed, 7 Oct 2009 18:41:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755427AbZJGWln (ORCPT ); Wed, 7 Oct 2009 18:41:43 -0400 Received: from einhorn.in-berlin.de ([192.109.42.8]:44046 "EHLO einhorn.in-berlin.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753060AbZJGWlm (ORCPT ); Wed, 7 Oct 2009 18:41:42 -0400 X-Envelope-From: stefanr@s5r6.in-berlin.de Date: Thu, 8 Oct 2009 00:40:38 +0200 (CEST) From: Stefan Richter Subject: [PATCH 3/8] firewire: cdev: reduce stack usage by ioctl_dispatch To: linux1394-devel@lists.sourceforge.net cc: linux-kernel@vger.kernel.org In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; CHARSET=us-ascii Content-Disposition: INLINE Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3130 Lines: 87 Shrink the stack-allocated ioctl argument buffer from 256 to 40 bytes. This is the maximum of what we currently need for all ioctls. Also, turn runtime checks of the buffer size into compile-time checks. This involves a few more lines of code but they are all taken care of by the compiler's dead code elimination, and this way the buffer size should actually be a little easier to update when new ioctls are added. Signed-off-by: Stefan Richter --- drivers/firewire/core-cdev.c | 41 ++++++++++++++++++++++++++--------- 1 file changed, 30 insertions(+), 11 deletions(-) Index: linux-2.6.31/drivers/firewire/core-cdev.c =================================================================== --- linux-2.6.31.orig/drivers/firewire/core-cdev.c +++ linux-2.6.31/drivers/firewire/core-cdev.c @@ -1299,28 +1299,47 @@ static int (* const ioctl_handlers[])(st static int dispatch_ioctl(struct client *client, unsigned int cmd, void __user *arg) { - char buffer[256]; + char buffer[40]; int ret; +#define check_ioctl_size(x) BUILD_BUG_ON(_IOC_SIZE(x) > sizeof(buffer)) + + check_ioctl_size(FW_CDEV_IOC_GET_INFO); + check_ioctl_size(FW_CDEV_IOC_SEND_REQUEST); + check_ioctl_size(FW_CDEV_IOC_ALLOCATE); + check_ioctl_size(FW_CDEV_IOC_DEALLOCATE); + check_ioctl_size(FW_CDEV_IOC_SEND_RESPONSE); + check_ioctl_size(FW_CDEV_IOC_INITIATE_BUS_RESET); + check_ioctl_size(FW_CDEV_IOC_ADD_DESCRIPTOR); + check_ioctl_size(FW_CDEV_IOC_REMOVE_DESCRIPTOR); + check_ioctl_size(FW_CDEV_IOC_CREATE_ISO_CONTEXT); + check_ioctl_size(FW_CDEV_IOC_QUEUE_ISO); + check_ioctl_size(FW_CDEV_IOC_START_ISO); + check_ioctl_size(FW_CDEV_IOC_STOP_ISO); + check_ioctl_size(FW_CDEV_IOC_GET_CYCLE_TIMER); + check_ioctl_size(FW_CDEV_IOC_ALLOCATE_ISO_RESOURCE); + check_ioctl_size(FW_CDEV_IOC_DEALLOCATE_ISO_RESOURCE); + check_ioctl_size(FW_CDEV_IOC_ALLOCATE_ISO_RESOURCE_ONCE); + check_ioctl_size(FW_CDEV_IOC_DEALLOCATE_ISO_RESOURCE_ONCE); + check_ioctl_size(FW_CDEV_IOC_GET_SPEED); + check_ioctl_size(FW_CDEV_IOC_SEND_BROADCAST_REQUEST); + check_ioctl_size(FW_CDEV_IOC_SEND_STREAM_PACKET); + if (_IOC_TYPE(cmd) != '#' || _IOC_NR(cmd) >= ARRAY_SIZE(ioctl_handlers)) return -EINVAL; - if (_IOC_DIR(cmd) & _IOC_WRITE) { - if (_IOC_SIZE(cmd) > sizeof(buffer) || - copy_from_user(buffer, arg, _IOC_SIZE(cmd))) - return -EFAULT; - } + if (_IOC_DIR(cmd) & _IOC_WRITE && + copy_from_user(buffer, arg, _IOC_SIZE(cmd))) + return -EFAULT; ret = ioctl_handlers[_IOC_NR(cmd)](client, buffer); if (ret < 0) return ret; - if (_IOC_DIR(cmd) & _IOC_READ) { - if (_IOC_SIZE(cmd) > sizeof(buffer) || - copy_to_user(arg, buffer, _IOC_SIZE(cmd))) - return -EFAULT; - } + if (_IOC_DIR(cmd) & _IOC_READ && + copy_to_user(arg, buffer, _IOC_SIZE(cmd))) + return -EFAULT; return ret; } -- Stefan Richter -=====-==--= =-=- -=--- http://arcgraph.de/sr/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/