From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: [PATCH] ext4: Make the extent validity check more paranoid Date: Wed, 22 Apr 2009 21:29:34 -0400 Message-ID: <1240450174-25868-1-git-send-email-tytso@mit.edu> Cc: Theodore Ts'o To: linux-ext4@vger.kernel.org Return-path: Received: from THUNK.ORG ([69.25.196.29]:50247 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751110AbZDWB3h (ORCPT ); Wed, 22 Apr 2009 21:29:37 -0400 Sender: linux-ext4-owner@vger.kernel.org List-ID: Instead of just checking that the extent block number is greater or equal than s_first_data_block, make sure it it is not pointing into the block group descriptors, since that is clearly wrong. This helps prevent filesystem from getting very badly corrupted in case an extent block is corrupted. Signed-off-by: "Theodore Ts'o" --- fs/ext4/extents.c | 18 ++++++++++++------ 1 files changed, 12 insertions(+), 6 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 6132353..c28ffe2 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -326,11 +326,14 @@ ext4_ext_max_entries(struct inode *inode, int depth) static int ext4_valid_extent(struct inode *inode, struct ext4_extent *ext) { - ext4_fsblk_t block = ext_pblock(ext); + ext4_fsblk_t block = ext_pblock(ext), valid_block; int len = ext4_ext_get_actual_len(ext); struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es; - if (unlikely(block < le32_to_cpu(es->s_first_data_block) || - ((block + len) > ext4_blocks_count(es)))) + + valid_block = le32_to_cpu(es->s_first_data_block) + + EXT4_SB(inode->i_sb)->s_gdb_count; + if (unlikely(block <= valid_block || + ((block + len) > ext4_blocks_count(es)))) return 0; else return 1; @@ -339,10 +342,13 @@ static int ext4_valid_extent(struct inode *inode, struct ext4_extent *ext) static int ext4_valid_extent_idx(struct inode *inode, struct ext4_extent_idx *ext_idx) { - ext4_fsblk_t block = idx_pblock(ext_idx); + ext4_fsblk_t block = idx_pblock(ext_idx), valid_block; struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es; - if (unlikely(block < le32_to_cpu(es->s_first_data_block) || - (block >= ext4_blocks_count(es)))) + + valid_block = le32_to_cpu(es->s_first_data_block) + + EXT4_SB(inode->i_sb)->s_gdb_count; + if (unlikely(block <= valid_block || + (block >= ext4_blocks_count(es)))) return 0; else return 1; -- 1.5.6.3