Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760328AbXKHLHA (ORCPT ); Thu, 8 Nov 2007 06:07:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756698AbXKHLGv (ORCPT ); Thu, 8 Nov 2007 06:06:51 -0500 Received: from [222.73.24.84] ([222.73.24.84]:49488 "EHLO song.cn.fujitsu.com" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1755670AbXKHLGu (ORCPT ); Thu, 8 Nov 2007 06:06:50 -0500 Message-ID: <4732EDD2.2050406@cn.fujitsu.com> Date: Thu, 08 Nov 2007 19:06:58 +0800 From: Miao Xie User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: gregkh@suse.de CC: linux-kernel@vger.kernel.org Subject: [PATCH] sysfs: fix off-by-one error in fill_read_buffer Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1713 Lines: 51 Hi,everyone. I found that there is a off-by-one problem in the following code. Version: 2.6.24-rc2 File: fs/sysfs/file.c:118-122 Function: fill_read_buffer -------------------------------------------------------------------- count = ops->show(kobj, attr_sd->s_attr.attr, buffer->page); sysfs_put_active_two(attr_sd); BUG_ON(count > (ssize_t)PAGE_SIZE); -------------------------------------------------------------------- Because according to the specification of the sysfs and the implement of the show methods, the show methods return the number of bytes which would be generated for the given input, excluding the trailing null.So if the return value of the show methods equals PAGE_SIZE - 1, the buffer is full in fact. And if the return value equals PAGE_SIZE, the resulting string was already truncated,or buffer overflow occurred. This patch fixes an off-by-one error in fill_read_buffer. Signed-off-by: Miao Xie --- fs/sysfs/file.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index 27d1785..f98d66d 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -119,7 +119,7 @@ static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer sysfs_put_active_two(attr_sd); - BUG_ON(count > (ssize_t)PAGE_SIZE); + BUG_ON(count >= (ssize_t)PAGE_SIZE); if (count >= 0) { buffer->needs_read_fill = 0; buffer->count = count; -- 1.5.3 - 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/