From: akpm@linux-foundation.org Subject: + ext4-add-block-bitmap-validation.patch added to -mm tree Date: Mon, 19 Nov 2007 23:20:08 -0800 Message-ID: <200711200720.lAK7K8Hu020976@imap1.linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Cc: aneesh.kumar@linux.vnet.ibm.com, linux-ext4@vger.kernel.org To: mm-commits@vger.kernel.org Return-path: Sender: mm-commits-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org The patch titled ext4: add block bitmap validation has been added to the -mm tree. Its filename is ext4-add-block-bitmap-validation.patch *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this ------------------------------------------------------ Subject: ext4: add block bitmap validation 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 Cc: Signed-off-by: Andrew Morton --- fs/ext4/balloc.c | 99 ++++++++++++++++++++++++++++++++++++--------- 1 file changed, 81 insertions(+), 18 deletions(-) diff -puN fs/ext4/balloc.c~ext4-add-block-bitmap-validation fs/ext4/balloc.c --- a/fs/ext4/balloc.c~ext4-add-block-bitmap-validation +++ a/fs/ext4/balloc.c @@ -189,13 +189,65 @@ struct ext4_group_desc * ext4_get_group_ 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 if (!desc) return NULL; bitmap_blk = ext4_block_bitmap(sb, desc); - 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); + bh = sb_getblk(sb, bitmap_blk); + if (unlikely(!bh)) { + ext4_error(sb, __FUNCTION__, + "Cannot read block bitmap - " + "block_group = %d, block_bitmap = %llu", + block_group, bitmap_blk); + return NULL; } - if (!bh) - ext4_error (sb, __FUNCTION__, + if (bh_uptodate_or_lock(bh)) + return bh; + + if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) { + ext4_init_block_bitmap(sb, bh, block_group, desc); + set_buffer_uptodate(bh); + unlock_buffer(bh); + return bh; + } + if (bh_submit_read(bh) < 0) { + brelse(bh); + ext4_error(sb, __FUNCTION__, "Cannot read block bitmap - " - "block_group = %lu, block_bitmap = %llu", + "block_group = %d, block_bitmap = %llu", block_group, bitmap_blk); + return NULL; + } + if (!ext4_valid_block_bitmap(sb, desc, block_group, bh)) { + brelse(bh); + return NULL; + } + return bh; } /* _ Patches currently in -mm which might be from aneesh.kumar@linux.vnet.ibm.com are ext2-return-after-ext2_error-in-case-of-failures.patch ext2-change-the-default-behaviour-on-error.patch add-buffer-head-related-helper-functions.patch ext2-add-block-bitmap-validation.patch ext3-add-block-bitmap-validation.patch ext4-add-block-bitmap-validation.patch ext3-return-after-ext3_error-in-case-of-failures.patch ext3-change-the-default-behaviour-on-error.patch