From: Theodore Ts'o Subject: [PATCH FOR-STABLE-2.6.28 22/24] ext4: Add sanity check to make_indexed_dir Date: Tue, 17 Feb 2009 10:32:40 -0500 Message-ID: <1234884762-13580-23-git-send-email-tytso@mit.edu> References: <1234884762-13580-1-git-send-email-tytso@mit.edu> <1234884762-13580-2-git-send-email-tytso@mit.edu> <1234884762-13580-3-git-send-email-tytso@mit.edu> <1234884762-13580-4-git-send-email-tytso@mit.edu> <1234884762-13580-5-git-send-email-tytso@mit.edu> <1234884762-13580-6-git-send-email-tytso@mit.edu> <1234884762-13580-7-git-send-email-tytso@mit.edu> <1234884762-13580-8-git-send-email-tytso@mit.edu> <1234884762-13580-9-git-send-email-tytso@mit.edu> <1234884762-13580-10-git-send-email-tytso@mit.edu> <1234884762-13580-11-git-send-email-tytso@mit.edu> <1234884762-13580-12-git-send-email-tytso@mit.edu> <1234884762-13580-13-git-send-email-tytso@mit.edu> <1234884762-13580-14-git-send-email-tytso@mit.edu> <1234884762-13580-15-git-send-email-tytso@mit.edu> <1234884762-13580-16-git-send-email-tytso@mit.edu> <1234884762-13580-17-git-send-email-tytso@mit.edu> <1234884762-13580-18-git-send-email-tytso@mit.edu> <1234884762-13580-19-git-send-email-tytso@mit.edu> <1234884762-13580-20-git-send-email-tytso@mit.edu> <1234884762-13580-21-git-send-email-tytso@mit.edu> <1234884762-13580-22-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]:33265 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752172AbZBQQLQ (ORCPT ); Tue, 17 Feb 2009 11:11:16 -0500 In-Reply-To: <1234884762-13580-22-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 dc0b16a..da94b20 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -1372,7 +1372,7 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry, struct fake_dirent *fde; blocksize = dir->i_sb->s_blocksize; - dxtrace(printk(KERN_DEBUG "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); @@ -1381,6 +1381,20 @@ 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); @@ -1389,11 +1403,6 @@ 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