On Thu 23-04-20 16:17:53, Ritesh Harjani wrote:
> ext4 supports max number of logical blocks in a file to be 0xffffffff.
> (This is since ext4_extent's ee_block is __le32).
> This means that EXT4_MAX_LOGICAL_BLOCK should be 0xfffffffe (starting
> from 0 logical offset). This patch fixes this.
>
> The issue was seen when ext4 moved to iomap_fiemap API and when
> overlayfs was mounted on top of ext4. Since overlayfs was missing
> filemap_check_ranges(), so it could pass a arbitrary huge length which
> lead to overflow of map.m_len logic.
>
> This patch fixes that.
>
> Fixes: d3b6f23f7167 ("ext4: move ext4_fiemap to use iomap framework")
> Reported-by: syzbot+77fa5bdb65cc39711820@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
The patch looks good to me. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> fs/ext4/ext4.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 91eb4381cae5..ad2dbf6e4924 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -722,7 +722,7 @@ enum {
> #define EXT4_MAX_BLOCK_FILE_PHYS 0xFFFFFFFF
>
> /* Max logical block we can support */
> -#define EXT4_MAX_LOGICAL_BLOCK 0xFFFFFFFF
> +#define EXT4_MAX_LOGICAL_BLOCK 0xFFFFFFFE
>
> /*
> * Structure of an inode on the disk
> --
> 2.21.0
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
