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@xxxxxxxxxxxxxxxxxx>
---
fs/ext3/balloc.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++-----
1 files changed, 69 insertions(+), 8 deletions(-)
diff --git a/fs/ext3/balloc.c b/fs/ext3/balloc.c
index a8ba7e8..8f732b8 100644
--- a/fs/ext3/balloc.c
+++ b/fs/ext3/balloc.c
@@ -80,13 +80,52 @@ struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb,
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 */
+ return 0;
+ }
+ /* 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 */
+ return 0;
+ }
+ /* 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,
+ EXT3_SB(sb)->s_itb_per_group + 1,
+ offset);
+ if (next_zero_bit >= offset + EXT3_SB(sb)->s_itb_per_group)
+ /* good bitmap for inode tables */
+ return 1;
+
+ 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.
*/
@@ -95,17 +134,39 @@ read_block_bitmap(struct super_block *sb, unsigned int block_group)
{
struct ext3_group_desc * desc;
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)
- goto error_out;
- bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap));
- if (!bh)
- ext3_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)) {
+ 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 (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));
-error_out:
+ return NULL;
+ }
+ if (!ext3_valid_block_bitmap(sb, desc, block_group, bh)) {
+ brelse(bh);
+ ext3_error(sb, __FUNCTION__,
+ "Invalid block bitmap - "
+ "block_group = %d, block = %lu",
+ block_group, bitmap_blk);
+ return NULL;
+ }
return bh;
}
/*
--
1.5.3.5.652.gf192c-dirty
-
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