On Thu, Sep 26, 2013 at 05:03:34PM -0700, Darrick J. Wong wrote:
> Perform a quick sanity check of bitmap and inode table block numbers when
> loading them, and if there's something suspicious, mark the block group
> corrupt.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> fs/ext4/balloc.c | 5 +++++
> fs/ext4/ext4.h | 2 ++
> fs/ext4/ialloc.c | 4 ++++
> fs/ext4/inode.c | 6 ++++++
> fs/ext4/super.c | 21 +++++++++++++++++++++
> 5 files changed, 38 insertions(+)
>
>
> diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
> index 4390f9f..3d79bfe 100644
> --- a/fs/ext4/balloc.c
> +++ b/fs/ext4/balloc.c
> @@ -396,11 +396,16 @@ ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
> struct ext4_group_desc *desc;
> struct buffer_head *bh;
> ext4_fsblk_t bitmap_blk;
> + struct ext4_group_info *grp;
>
> desc = ext4_get_group_desc(sb, block_group, NULL);
> if (!desc)
> return NULL;
> bitmap_blk = ext4_block_bitmap(sb, desc);
> + if (!ext4_is_sane_bgdata_location(sb, block_group, bitmap_blk)) {
> + grp = ext4_get_group_info(sb, block_group);
> + set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
Why don't return NULL directly? If we found that the location of bitmap
is insane, we shouldn't read this bitmap.
- Zheng
> + }
> bh = sb_getblk(sb, bitmap_blk);
> if (unlikely(!bh)) {
> ext4_error(sb, "Cannot get buffer for block bitmap - "
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index af815ea..afb1bb2 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -2531,6 +2531,8 @@ static inline void ext4_unlock_group(struct super_block *sb,
> spin_unlock(ext4_group_lock_ptr(sb, group));
> }
>
> +int ext4_is_sane_bgdata_location(struct super_block *sb, ext4_group_t grp,
> + ext4_fsblk_t blk);
> /*
> * Block validity checking
> */
> diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
> index 137193f..242250d 100644
> --- a/fs/ext4/ialloc.c
> +++ b/fs/ext4/ialloc.c
> @@ -122,6 +122,10 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
> return NULL;
>
> bitmap_blk = ext4_inode_bitmap(sb, desc);
> + if (!ext4_is_sane_bgdata_location(sb, block_group, bitmap_blk)) {
> + grp = ext4_get_group_info(sb, block_group);
> + set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
> + }
> bh = sb_getblk(sb, bitmap_blk);
> if (unlikely(!bh)) {
> ext4_error(sb, "Cannot read inode bitmap - "
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 0d424d7..c5af22e 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3795,6 +3795,7 @@ static int __ext4_get_inode_loc(struct inode *inode,
> struct super_block *sb = inode->i_sb;
> ext4_fsblk_t block;
> int inodes_per_block, inode_offset;
> + struct ext4_group_info *grp;
>
> iloc->bh = NULL;
> if (!ext4_valid_inum(sb, inode->i_ino))
> @@ -3814,6 +3815,11 @@ static int __ext4_get_inode_loc(struct inode *inode,
> block = ext4_inode_table(sb, gdp) + (inode_offset / inodes_per_block);
> iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);
>
> + if (!ext4_is_sane_bgdata_location(sb, iloc->block_group, block)) {
> + grp = ext4_get_group_info(sb, iloc->block_group);
> + set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
> + return -EIO;
> + }
> bh = sb_getblk(sb, block);
> if (unlikely(!bh))
> return -ENOMEM;
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 2c2e6cb..d22248e 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -2049,6 +2049,27 @@ void ext4_group_desc_csum_set(struct super_block *sb, __u32 block_group,
> gdp->bg_checksum = ext4_group_desc_csum(EXT4_SB(sb), block_group, gdp);
> }
>
> +/* returns 1 if the location of a blockgroup data item seems sane */
> +int ext4_is_sane_bgdata_location(struct super_block *sb, ext4_group_t grp,
> + ext4_fsblk_t blk)
> +{
> + struct ext4_sb_info *sbi = EXT4_SB(sb);
> + ext4_fsblk_t first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
> + ext4_fsblk_t last_block;
> +
> + if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
> + last_block = ext4_blocks_count(sbi->s_es) - 1;
> + else {
> + first_block += grp * sbi->s_blocks_per_group;
> + last_block = first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
> + }
> +
> + if (last_block >= ext4_blocks_count(sbi->s_es))
> + last_block = ext4_blocks_count(sbi->s_es) - 1;
> +
> + return blk >= first_block && blk <= last_block;
> +}
> +
> /* Called at mount-time, super-block is locked */
> static int ext4_check_descriptors(struct super_block *sb,
> ext4_group_t *first_not_zeroed)
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
