From 7c9e69faa28027913ee059c285a5ea8382e24b5d Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Tue, 16 Oct 2007 23:27:02 -0700 Subject: ext2/ext3/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 by ext4_blk_bitmap, ext4_inode_bitmap and ext4_inode_table. Validate the block bitmap against these blocks. [akpm@linux-foundation.org: cleanups] Signed-off-by: Aneesh Kumar K.V Signed-off-by: Andreas Dilger Acked-by: Mingming Cao Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ext4/balloc.c | 62 ++++++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 47 insertions(+), 15 deletions(-) (limited to 'fs/ext4/balloc.c') diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c index 8d59eec2e82b..b74bf4368441 100644 --- a/fs/ext4/balloc.c +++ b/fs/ext4/balloc.c @@ -100,6 +100,15 @@ struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb, return desc; } +static inline int +block_in_use(ext4_fsblk_t block, struct super_block *sb, unsigned char *map) +{ + ext4_grpblk_t offset; + + ext4_get_group_no_and_offset(sb, block, NULL, &offset); + return ext4_test_bit (offset, map); +} + /** * read_block_bitmap() * @sb: super block @@ -113,21 +122,53 @@ struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb, static struct buffer_head * read_block_bitmap(struct super_block *sb, unsigned int block_group) { + int i; struct ext4_group_desc * desc; struct buffer_head * bh = NULL; + ext4_fsblk_t bitmap_blk; desc = ext4_get_group_desc (sb, block_group, NULL); if (!desc) - goto error_out; - bh = sb_bread(sb, ext4_block_bitmap(sb, desc)); + return NULL; + bitmap_blk = ext4_block_bitmap(sb, desc); + bh = sb_bread(sb, bitmap_blk); if (!bh) - ext4_error (sb, "read_block_bitmap", + ext4_error (sb, __FUNCTION__, "Cannot read block bitmap - " "block_group = %d, block_bitmap = %llu", - block_group, - ext4_block_bitmap(sb, desc)); -error_out: + block_group, bitmap_blk); + + /* check whether block bitmap block number is set */ + if (!block_in_use(bitmap_blk, sb, bh->b_data)) { + /* bad block bitmap */ + goto error_out; + } + + /* check whether the inode bitmap block number is set */ + bitmap_blk = ext4_inode_bitmap(sb, desc); + if (!block_in_use(bitmap_blk, sb, bh->b_data)) { + /* bad block bitmap */ + goto error_out; + } + /* check whether the inode table block number is set */ + bitmap_blk = ext4_inode_table(sb, desc); + for (i = 0; i < EXT4_SB(sb)->s_itb_per_group; i++, bitmap_blk++) { + if (!block_in_use(bitmap_blk, sb, bh->b_data)) { + /* bad block bitmap */ + goto error_out; + } + } + return bh; + +error_out: + brelse(bh); + ext4_error(sb, __FUNCTION__, + "Invalid block bitmap - " + "block_group = %d, block = %llu", + block_group, bitmap_blk); + return NULL; + } /* * The reservation window structure operations @@ -1747,15 +1788,6 @@ ext4_fsblk_t ext4_count_free_blocks(struct super_block *sb) #endif } -static inline int -block_in_use(ext4_fsblk_t block, struct super_block *sb, unsigned char *map) -{ - ext4_grpblk_t offset; - - ext4_get_group_no_and_offset(sb, block, NULL, &offset); - return ext4_test_bit (offset, map); -} - static inline int test_root(int a, int b) { int num = b; -- cgit v1.2.2