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author | Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> | 2008-01-29 04:58:27 (GMT) |
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committer | Theodore Ts'o <tytso@mit.edu> | 2008-01-29 04:58:27 (GMT) |
commit | abcb2947c91130426539f209f7a473a67a1f6663 (patch) | |
tree | 4305e34c0a129c1351d9acabd254b0f896617470 /fs/ext4/balloc.c | |
parent | 389d1b083c767a360ec84b27a95da06244becec8 (diff) | |
download | linux-fsl-qoriq-abcb2947c91130426539f209f7a473a67a1f6663.tar.xz |
ext4: add block bitmap validation
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 <aneesh.kumar@linux.vnet.ibm.com>
Diffstat (limited to 'fs/ext4/balloc.c')
-rw-r--r-- | 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..d460223 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) { + put_bh(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)) { + put_bh(bh); + return NULL; + } + return bh; } /* |