From: Theodore Ts'o Subject: [PATCH FOR-STABLE-2.6.27 22/24] ext4: Add sanity check to make_indexed_dir Date: Tue, 17 Feb 2009 10:58:42 -0500 Message-ID: <1234886324-15105-23-git-send-email-tytso@mit.edu> References: <1234886324-15105-1-git-send-email-tytso@mit.edu> <1234886324-15105-2-git-send-email-tytso@mit.edu> <1234886324-15105-3-git-send-email-tytso@mit.edu> <1234886324-15105-4-git-send-email-tytso@mit.edu> <1234886324-15105-5-git-send-email-tytso@mit.edu> <1234886324-15105-6-git-send-email-tytso@mit.edu> <1234886324-15105-7-git-send-email-tytso@mit.edu> <1234886324-15105-8-git-send-email-tytso@mit.edu> <1234886324-15105-9-git-send-email-tytso@mit.edu> <1234886324-15105-10-git-send-email-tytso@mit.edu> <1234886324-15105-11-git-send-email-tytso@mit.edu> <1234886324-15105-12-git-send-email-tytso@mit.edu> <1234886324-15105-13-git-send-email-tytso@mit.edu> <1234886324-15105-14-git-send-email-tytso@mit.edu> <1234886324-15105-15-git-send-email-tytso@mit.edu> <1234886324-15105-16-git-send-email-tytso@mit.edu> <1234886324-15105-17-git-send-email-tytso@mit.edu> <1234886324-15105-18-git-send-email-tytso@mit.edu> <1234886324-15105-19-git-send-email-tytso@mit.edu> <1234886324-15105-20-git-send-email-tytso@mit.edu> <1234886324-15105-21-git-send-email-tytso@mit.edu> <1234886324-15105-22-git-send-email-tytso@mit.edu> Cc: linux-ext4@vger.kernel.org, Theodore Ts'o To: stable@kernel.org Return-path: Received: from thunk.org ([69.25.196.29]:56262 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752669AbZBQQPU (ORCPT ); Tue, 17 Feb 2009 11:15:20 -0500 In-Reply-To: <1234886324-15105-22-git-send-email-tytso@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: Make sure the rec_len field in the '..' entry is sane, lest we overrun the directory block and cause a kernel oops on a purposefully corrupted filesystem. Thanks to Sami Liedes for reporting this bug. http://bugzilla.kernel.org/show_bug.cgi?id=12430 Signed-off-by: "Theodore Ts'o" Cc: stable@kernel.org (cherry picked from commit e6b8bc09ba2075cd91fbffefcd2778b1a00bd76f) --- fs/ext4/namei.c | 21 +++++++++++++++------ 1 files changed, 15 insertions(+), 6 deletions(-) diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 8f0881b..4f3628f 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -1382,7 +1382,7 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry, struct fake_dirent *fde; blocksize = dir->i_sb->s_blocksize; - dxtrace(printk("Creating index\n")); + dxtrace(printk(KERN_DEBUG "Creating index: inode %lu\n", dir->i_ino)); retval = ext4_journal_get_write_access(handle, bh); if (retval) { ext4_std_error(dir->i_sb, retval); @@ -1391,6 +1391,20 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry, } root = (struct dx_root *) bh->b_data; + /* The 0th block becomes the root, move the dirents out */ + fde = &root->dotdot; + de = (struct ext4_dir_entry_2 *)((char *)fde + + ext4_rec_len_from_disk(fde->rec_len)); + if ((char *) de >= (((char *) root) + blocksize)) { + ext4_error(dir->i_sb, __func__, + "invalid rec_len for '..' in inode %lu", + dir->i_ino); + brelse(bh); + return -EIO; + } + len = ((char *) root) + blocksize - (char *) de; + + /* Allocate new block for the 0th block's dirents */ bh2 = ext4_append (handle, dir, &block, &retval); if (!(bh2)) { brelse(bh); @@ -1399,11 +1413,6 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry, EXT4_I(dir)->i_flags |= EXT4_INDEX_FL; data1 = bh2->b_data; - /* The 0th block becomes the root, move the dirents out */ - fde = &root->dotdot; - de = (struct ext4_dir_entry_2 *)((char *)fde + - ext4_rec_len_from_disk(fde->rec_len)); - len = ((char *) root) + blocksize - (char *) de; memcpy (data1, de, len); de = (struct ext4_dir_entry_2 *) data1; top = data1 + len; -- 1.5.6.3