Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=01584fa6456dafbaf5a94ad7fb2aa3e3ecd7a7ba
Commit: 01584fa6456dafbaf5a94ad7fb2aa3e3ecd7a7ba
Parent: 445a1d3e24b806bff01e422f0ddadf68e0eb5d0f
Author: Aneesh Kumar K.V <[EMAIL PROTECTED]>
AuthorDate: Wed Feb 6 01:40:08 2008 -0800
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Wed Feb 6 10:41:20 2008 -0800
ext2: 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 <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
fs/ext2/balloc.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++------
1 files changed, 72 insertions(+), 9 deletions(-)
diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
index 794008b..a51bdf8 100644
--- a/fs/ext2/balloc.c
+++ b/fs/ext2/balloc.c
@@ -69,9 +69,53 @@ struct ext2_group_desc * ext2_get_group_desc(struct
super_block * sb,
return desc + offset;
}
+static int ext2_valid_block_bitmap(struct super_block *sb,
+ struct ext2_group_desc *desc,
+ unsigned int block_group,
+ struct buffer_head *bh)
+{
+ ext2_grpblk_t offset;
+ ext2_grpblk_t next_zero_bit;
+ ext2_fsblk_t bitmap_blk;
+ ext2_fsblk_t group_first_block;
+
+ group_first_block = ext2_group_first_block_no(sb, block_group);
+
+ /* check whether block bitmap block number is set */
+ bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
+ offset = bitmap_blk - group_first_block;
+ if (!ext2_test_bit(offset, bh->b_data))
+ /* bad block bitmap */
+ goto err_out;
+
+ /* check whether the inode bitmap block number is set */
+ bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);
+ offset = bitmap_blk - group_first_block;
+ if (!ext2_test_bit(offset, bh->b_data))
+ /* bad block bitmap */
+ goto err_out;
+
+ /* check whether the inode table block number is set */
+ bitmap_blk = le32_to_cpu(desc->bg_inode_table);
+ offset = bitmap_blk - group_first_block;
+ next_zero_bit = ext2_find_next_zero_bit(bh->b_data,
+ offset + EXT2_SB(sb)->s_itb_per_group,
+ offset);
+ if (next_zero_bit >= offset + EXT2_SB(sb)->s_itb_per_group)
+ /* good bitmap for inode tables */
+ return 1;
+
+err_out:
+ ext2_error(sb, __FUNCTION__,
+ "Invalid block bitmap - "
+ "block_group = %d, block = %lu",
+ block_group, bitmap_blk);
+ return 0;
+}
+
/*
- * 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.
*/
@@ -80,17 +124,36 @@ read_block_bitmap(struct super_block *sb, unsigned int
block_group)
{
struct ext2_group_desc * desc;
struct buffer_head * bh = NULL;
-
- desc = ext2_get_group_desc (sb, block_group, NULL);
+ ext2_fsblk_t bitmap_blk;
+
+ desc = ext2_get_group_desc(sb, block_group, NULL);
if (!desc)
- goto error_out;
- bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap));
- if (!bh)
- ext2_error (sb, "read_block_bitmap",
+ return NULL;
+ bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
+ bh = sb_getblk(sb, bitmap_blk);
+ if (unlikely(!bh)) {
+ ext2_error(sb, __FUNCTION__,
"Cannot read block bitmap - "
"block_group = %d, block_bitmap = %u",
block_group, le32_to_cpu(desc->bg_block_bitmap));
-error_out:
+ return NULL;
+ }
+ if (likely(bh_uptodate_or_lock(bh)))
+ return bh;
+
+ if (bh_submit_read(bh) < 0) {
+ brelse(bh);
+ ext2_error(sb, __FUNCTION__,
+ "Cannot read block bitmap - "
+ "block_group = %d, block_bitmap = %u",
+ block_group, le32_to_cpu(desc->bg_block_bitmap));
+ return NULL;
+ }
+ if (!ext2_valid_block_bitmap(sb, desc, block_group, bh)) {
+ brelse(bh);
+ return NULL;
+ }
+
return bh;
}
-
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