From: Wang Sheng-Hui Subject: [PATCH] ext2: check xattr name_len before acquiring sem lock in ext2_xattr_get Date: Fri, 22 Jul 2011 22:06:24 +0800 Message-ID: <4E2983E0.3060208@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit To: linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, Jan Kara , "Theodore Ts'o" Return-path: Received: from mail-pz0-f42.google.com ([209.85.210.42]:57379 "EHLO mail-pz0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754455Ab1GVOGf (ORCPT ); Fri, 22 Jul 2011 10:06:35 -0400 Sender: linux-ext4-owner@vger.kernel.org List-ID: >From 667173a18b671896f933c5952fa211601d2e5ab0 Mon Sep 17 00:00:00 2001 From: Wang Sheng-Hui Date: Fri, 22 Jul 2011 08:50:13 -0500 Subject: [PATCH] ext2: check xattr name_len before acquiring sem lock in ext2_xattr_get The patch is against 3.0. In ext2_xattr_get, the code will acquire sem lock first, later check the length of xattr name_len > 255. It's kind of time consuming, and we should do the basic check before the time consuming acquiring sem lock. Signed-off-by: Wang Sheng-Hui --- fs/ext2/xattr.c | 10 +++++----- 1 files changed, 5 insertions(+), 5 deletions(-) diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c index 5299706..d27b71f 100644 --- a/fs/ext2/xattr.c +++ b/fs/ext2/xattr.c @@ -161,6 +161,10 @@ ext2_xattr_get(struct inode *inode, int name_index, const char *name, if (name == NULL) return -EINVAL; + name_len = strlen(name); + if (name_len > 255) + return -ERANGE; + down_read(&EXT2_I(inode)->xattr_sem); error = -ENODATA; if (!EXT2_I(inode)->i_file_acl) @@ -181,12 +185,8 @@ bad_block: ext2_error(inode->i_sb, "ext2_xattr_get", error = -EIO; goto cleanup; } - /* find named attribute */ - name_len = strlen(name); - error = -ERANGE; - if (name_len > 255) - goto cleanup; + /* find named attribute */ entry = FIRST_ENTRY(bh); while (!IS_LAST_ENTRY(entry)) { struct ext2_xattr_entry *next = -- 1.7.1