From: Kazuya Mio Subject: [PATCH V2] ext4: FIBMAP ioctl causes BUG_ON due to handle EXT_MAX_BLOCKS Date: Fri, 4 Apr 2014 08:02:58 +0000 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset="iso-2022-jp" Content-Transfer-Encoding: 8BIT Cc: "linux-ext4@vger.kernel.org" To: "tytso@mit.edu" , "adilger.kernel@dilger.ca" Return-path: Received: from TYO201.gate.nec.co.jp ([210.143.35.51]:51210 "EHLO tyo201.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750755AbaDDIE0 convert rfc822-to-8bit (ORCPT ); Fri, 4 Apr 2014 04:04:26 -0400 Content-Language: ja-JP Sender: linux-ext4-owner@vger.kernel.org List-ID: When we try to get 2^32-1 block of the file which has the extent (ee_block=2^32-2, ee_len=1) with FIBMAP ioctl, it causes BUG_ON in ext4_ext_put_gap_in_cache(). To avoid the problem, ext4_map_blocks() needs to check the file logical block number. ext4_ext_put_gap_in_cache() called via ext4_map_blocks() cannot handle 2^32-1 because the maximum file logical block number is 2^32-2. Note that ext4_ind_map_blocks() returns -EIO when the block number is invalid. So ext4_map_blocks() should also return the same errno. Signed-off-by: Kazuya Mio --- fs/ext4/inode.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 24bfd7f..b0d5860 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -515,6 +515,10 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode, "logical block %lu\n", inode->i_ino, flags, map->m_len, (unsigned long) map->m_lblk); + /* We can handle the block number less than EXT_MAX_BLOCKS */ + if (unlikely(map->m_lblk >= EXT_MAX_BLOCKS)) + return -EIO; + /* Lookup extent status tree firstly */ if (ext4_es_lookup_extent(inode, map->m_lblk, &es)) { ext4_es_lru_add(inode);