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 <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andreas Dilger <adilger@clusterfs.com>
Acked-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 8d59eec..b74bf43 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -100,6 +100,15 @@
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 @@
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 @@
#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;