Re: [Qemu-block] [Qemu-devel] [PATCH v2 for-2.10 2/4] block/vhdx: check for offset overflow to bdrv_truncate()

[Philippe Mathieu-Daudé]

On Mon, Aug 7, 2017 at 9:38 AM, Jeff Cody <address@hidden> wrote:
> VHDX uses uint64_t types for most offsets, following the VHDX spec.
> However, bdrv_truncate() takes an int64_t value for the truncating
> offset.  Check for overflow before calling bdrv_truncate().
>
> While we are here, replace the bit shifting with QEMU_ALIGN_UP as well.
>
> N.B.: For a compliant image this is not an issue, as the maximum VHDX
> image size is defined per the spec to be 64TB.
>
> Reviewed-by: Eric Blake <address@hidden>
> Reviewed-by: Kevin Wolf <address@hidden>
> Signed-off-by: Jeff Cody <address@hidden>

Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

> ---
>  block/vhdx-log.c | 6 +++++-
>  block/vhdx.c     | 3 +++
>  2 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/block/vhdx-log.c b/block/vhdx-log.c
> index 2e26fd4..9597223 100644
> --- a/block/vhdx-log.c
> +++ b/block/vhdx-log.c
> @@ -553,7 +553,11 @@ static int vhdx_log_flush(BlockDriverState *bs, 
> BDRVVHDXState *s,
>              new_file_size = desc_entries->hdr.last_file_offset;
>              if (new_file_size % (1024*1024)) {
>                  /* round up to nearest 1MB boundary */
> -                new_file_size = ((new_file_size >> 20) + 1) << 20;
> +                new_file_size = QEMU_ALIGN_UP(new_file_size, MiB);
> +                if (new_file_size > INT64_MAX) {
> +                    ret = -EINVAL;
> +                    goto exit;
> +                }
>                  bdrv_truncate(bs->file, new_file_size, PREALLOC_MODE_OFF, 
> NULL);
>              }
>          }
> diff --git a/block/vhdx.c b/block/vhdx.c
> index 37224b8..7ae4589 100644
> --- a/block/vhdx.c
> +++ b/block/vhdx.c
> @@ -1177,6 +1177,9 @@ static int vhdx_allocate_block(BlockDriverState *bs, 
> BDRVVHDXState *s,
>
>      /* per the spec, the address for a block is in units of 1MB */
>      *new_offset = ROUND_UP(*new_offset, 1024 * 1024);
> +    if (*new_offset > INT64_MAX) {
> +        return -EINVAL;
> +    }
>
>      return bdrv_truncate(bs->file, *new_offset + s->block_size,
>                           PREALLOC_MODE_OFF, NULL);
> --
> 2.9.4
>
>