From: Greg KH Subject: [patch 34/36] ext4: Add sanity check to make_indexed_dir Date: Wed, 18 Feb 2009 14:29:58 -0800 Message-ID: <20090218222958.GI10668@kroah.com> References: <20090218222447.432108614@mini.kroah.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Justin Forbes , Zwane Mwaikambo , Theodore Ts'o , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , Willy Tarreau , Rodrigo Rubira Branco , Jake Edge , Eugene Teo , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, linux-ext4@vger.kernel.org To: linux-kernel@vger.kernel.org, stable@kernel.org Return-path: Received: from kroah.org ([198.145.64.141]:35123 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757962AbZBRWcZ (ORCPT ); Wed, 18 Feb 2009 17:32:25 -0500 Content-Disposition: inline; filename="ext4-add-sanity-check-to-make_indexed_dir.patch" In-Reply-To: <20090218222841.GA10668@kroah.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: "Theodore Ts'o" (cherry picked from commit e6b8bc09ba2075cd91fbffefcd2778b1a00bd76f) 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" Signed-off-by: Greg Kroah-Hartman --- fs/ext4/namei.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -1382,7 +1382,7 @@ static int make_indexed_dir(handle_t *ha 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 *ha } 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 *ha 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;