提交 f762e905 编写于 作者: A Aneesh Kumar K.V 提交者: Linus Torvalds

ext3: 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: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 01584fa6
...@@ -80,13 +80,57 @@ struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb, ...@@ -80,13 +80,57 @@ struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb,
return desc + offset; return desc + offset;
} }
static int ext3_valid_block_bitmap(struct super_block *sb,
struct ext3_group_desc *desc,
unsigned int block_group,
struct buffer_head *bh)
{
ext3_grpblk_t offset;
ext3_grpblk_t next_zero_bit;
ext3_fsblk_t bitmap_blk;
ext3_fsblk_t group_first_block;
group_first_block = ext3_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 (!ext3_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 (!ext3_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 = ext3_find_next_zero_bit(bh->b_data,
offset + EXT3_SB(sb)->s_itb_per_group,
offset);
if (next_zero_bit >= offset + EXT3_SB(sb)->s_itb_per_group)
/* good bitmap for inode tables */
return 1;
err_out:
ext3_error(sb, __FUNCTION__,
"Invalid block bitmap - "
"block_group = %d, block = %lu",
block_group, bitmap_blk);
return 0;
}
/** /**
* read_block_bitmap() * read_block_bitmap()
* @sb: super block * @sb: super block
* @block_group: given block group * @block_group: given block group
* *
* Read the bitmap for a given block_group, reading into the specified * Read the bitmap for a given block_group,and validate the
* slot in the superblock's bitmap cache. * bits for block/inode/inode tables are set in the bitmaps
* *
* Return buffer_head on success or NULL in case of failure. * Return buffer_head on success or NULL in case of failure.
*/ */
...@@ -95,17 +139,35 @@ read_block_bitmap(struct super_block *sb, unsigned int block_group) ...@@ -95,17 +139,35 @@ read_block_bitmap(struct super_block *sb, unsigned int block_group)
{ {
struct ext3_group_desc * desc; struct ext3_group_desc * desc;
struct buffer_head * bh = NULL; struct buffer_head * bh = NULL;
ext3_fsblk_t bitmap_blk;
desc = ext3_get_group_desc (sb, block_group, NULL); desc = ext3_get_group_desc(sb, block_group, NULL);
if (!desc) if (!desc)
goto error_out; return NULL;
bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap)); bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
if (!bh) bh = sb_getblk(sb, bitmap_blk);
ext3_error (sb, "read_block_bitmap", if (unlikely(!bh)) {
ext3_error(sb, __FUNCTION__,
"Cannot read block bitmap - " "Cannot read block bitmap - "
"block_group = %d, block_bitmap = %u", "block_group = %d, block_bitmap = %u",
block_group, le32_to_cpu(desc->bg_block_bitmap)); 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);
ext3_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 (!ext3_valid_block_bitmap(sb, desc, block_group, bh)) {
brelse(bh);
return NULL;
}
return bh; return bh;
} }
/* /*
......
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册