Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762421AbYAVDNv (ORCPT ); Mon, 21 Jan 2008 22:13:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760104AbYAVDGt (ORCPT ); Mon, 21 Jan 2008 22:06:49 -0500 Received: from BISCAYNE-ONE-STATION.MIT.EDU ([18.7.7.80]:32924 "EHLO biscayne-one-station.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758162AbYAVDGr (ORCPT ); Mon, 21 Jan 2008 22:06:47 -0500 From: "Theodore Ts'o" To: linux-kernel@vger.kernel.org Cc: "Aneesh Kumar K.V" Subject: [PATCH 24/49] ext4: add block bitmap validation Date: Mon, 21 Jan 2008 22:02:03 -0500 Message-Id: <1200970948-17903-25-git-send-email-tytso@mit.edu> X-Mailer: git-send-email 1.5.4.rc3.31.g1271-dirty In-Reply-To: <1200970948-17903-24-git-send-email-tytso@mit.edu> References: <1200970948-17903-1-git-send-email-tytso@mit.edu> <1200970948-17903-2-git-send-email-tytso@mit.edu> <1200970948-17903-3-git-send-email-tytso@mit.edu> <1200970948-17903-4-git-send-email-tytso@mit.edu> <1200970948-17903-5-git-send-email-tytso@mit.edu> <1200970948-17903-6-git-send-email-tytso@mit.edu> <1200970948-17903-7-git-send-email-tytso@mit.edu> <1200970948-17903-8-git-send-email-tytso@mit.edu> <1200970948-17903-9-git-send-email-tytso@mit.edu> <1200970948-17903-10-git-send-email-tytso@mit.edu> <1200970948-17903-11-git-send-email-tytso@mit.edu> <1200970948-17903-12-git-send-email-tytso@mit.edu> <1200970948-17903-13-git-send-email-tytso@mit.edu> <1200970948-17903-14-git-send-email-tytso@mit.edu> <1200970948-17903-15-git-send-email-tytso@mit.edu> <1200970948-17903-16-git-send-email-tytso@mit.edu> <1200970948-17903-17-git-send-email-tytso@mit.edu> <1200970948-17903-18-git-send-email-tytso@mit.edu> <1200970948-17903-19-git-send-email-tytso@mit.edu> <1200970948-17903-20-git-send-email-tytso@mit.edu> <1200970948-17903-21-git-send-email-tytso@mit.edu> <1200970948-17903-22-git-send-email-tytso@mit.edu> <1200970948-17903-23-git-send-email-tytso@mit.edu> <1200970948-17903-24-git-send-email-tytso@mit.edu> X-Spam-Flag: NO X-Spam-Score: 0.00 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4562 Lines: 145 From: Aneesh Kumar K.V When a new block bitmap is read from disk in read_block_bitmap() there are a few bits that should ALWAYS be set. In particular, the blocks given corresponding to block bitmap, inode bitmap and inode tables. Validate the block bitmap against these blocks. Signed-off-by: Aneesh Kumar K.V --- fs/ext4/balloc.c | 99 ++++++++++++++++++++++++++++++++++++++++++++---------- 1 files changed, 81 insertions(+), 18 deletions(-) diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c index ff3428e..a9140ea 100644 --- a/fs/ext4/balloc.c +++ b/fs/ext4/balloc.c @@ -189,13 +189,65 @@ struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb, return desc; } +static int ext4_valid_block_bitmap(struct super_block *sb, + struct ext4_group_desc *desc, + unsigned int block_group, + struct buffer_head *bh) +{ + ext4_grpblk_t offset; + ext4_grpblk_t next_zero_bit; + ext4_fsblk_t bitmap_blk; + ext4_fsblk_t group_first_block; + + if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) { + /* with FLEX_BG, the inode/block bitmaps and itable + * blocks may not be in the group at all + * so the bitmap validation will be skipped for those groups + * or it has to also read the block group where the bitmaps + * are located to verify they are set. + */ + return 1; + } + group_first_block = ext4_group_first_block_no(sb, block_group); + + /* check whether block bitmap block number is set */ + bitmap_blk = ext4_block_bitmap(sb, desc); + offset = bitmap_blk - group_first_block; + if (!ext4_test_bit(offset, bh->b_data)) + /* bad block bitmap */ + goto err_out; + + /* check whether the inode bitmap block number is set */ + bitmap_blk = ext4_inode_bitmap(sb, desc); + offset = bitmap_blk - group_first_block; + if (!ext4_test_bit(offset, bh->b_data)) + /* bad block bitmap */ + goto err_out; + + /* check whether the inode table block number is set */ + bitmap_blk = ext4_inode_table(sb, desc); + offset = bitmap_blk - group_first_block; + next_zero_bit = ext4_find_next_zero_bit(bh->b_data, + offset + EXT4_SB(sb)->s_itb_per_group, + offset); + if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group) + /* good bitmap for inode tables */ + return 1; + +err_out: + ext4_error(sb, __FUNCTION__, + "Invalid block bitmap - " + "block_group = %d, block = %llu", + block_group, bitmap_blk); + return 0; +} /** * read_block_bitmap() * @sb: super block * @block_group: given block group * - * Read the bitmap for a given block_group, reading into the specified - * slot in the superblock's bitmap cache. + * Read the bitmap for a given block_group,and validate the + * bits for block/inode/inode tables are set in the bitmaps * * Return buffer_head on success or NULL in case of failure. */ @@ -210,25 +262,36 @@ read_block_bitmap(struct super_block *sb, ext4_group_t block_group) if (!desc) return NULL; bitmap_blk = ext4_block_bitmap(sb, desc); + bh = sb_getblk(sb, bitmap_blk); + if (unlikely(!bh)) { + ext4_error(sb, __FUNCTION__, + "Cannot read block bitmap - " + "block_group = %d, block_bitmap = %llu", + (int)block_group, (unsigned long long)bitmap_blk); + return NULL; + } + if (bh_uptodate_or_lock(bh)) + return bh; + if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) { - bh = sb_getblk(sb, bitmap_blk); - if (!buffer_uptodate(bh)) { - lock_buffer(bh); - if (!buffer_uptodate(bh)) { - ext4_init_block_bitmap(sb, bh, block_group, - desc); - set_buffer_uptodate(bh); - } - unlock_buffer(bh); - } - } else { - bh = sb_bread(sb, bitmap_blk); + ext4_init_block_bitmap(sb, bh, block_group, desc); + set_buffer_uptodate(bh); + unlock_buffer(bh); + return bh; } - if (!bh) - ext4_error (sb, __FUNCTION__, + if (bh_submit_read(bh) < 0) { + brelse(bh); + ext4_error(sb, __FUNCTION__, "Cannot read block bitmap - " - "block_group = %lu, block_bitmap = %llu", - block_group, bitmap_blk); + "block_group = %d, block_bitmap = %llu", + (int)block_group, (unsigned long long)bitmap_blk); + return NULL; + } + if (!ext4_valid_block_bitmap(sb, desc, block_group, bh)) { + brelse(bh); + return NULL; + } + return bh; } /* -- 1.5.4.rc3.31.g1271-dirty -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/