Re: [Qemu-devel] [PATCH 3/3] virtio-blk: Treat read/write beyond end as invalid

[Fam Zheng <famz@redhat.com>]

On Thu, 06/05 14:15, Markus Armbruster wrote:
> The block layer fails such reads and writes just fine.  However, they
> then get treated like valid operations that fail: the error action
> gets executed.  Unwanted; reporting the error to the guest is the only
> sensible action.
> 
> Reject them before passing them to the block layer.  This bypasses the
> error action and I/O accounting.
> 
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
>  hw/block/virtio-blk.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> index 2c68d0d..0b38049 100644
> --- a/hw/block/virtio-blk.c
> +++ b/hw/block/virtio-blk.c
> @@ -284,12 +284,19 @@ static void virtio_blk_handle_flush(VirtIOBlockReq *req, MultiReqBuffer *mrb)
>  static bool virtio_blk_sect_range_ok(VirtIOBlock *dev,
>                                       uint64_t sector, size_t size)
>  {
> +    uint64_t nb_sectors = size >> BDRV_SECTOR_BITS;
> +    uint64_t total_sectors;
> +
>      if (sector & dev->sector_mask) {
>          return false;
>      }
>      if (size % dev->conf->logical_block_size) {
>          return false;
>      }
> +    bdrv_get_geometry(dev->bs, &total_sectors);
> +    if (sector > total_sectors || nb_sectors > total_sectors - sector) {
> +        return false;
> +    }
>      return true;
>  }
>  
> -- 
> 1.9.3
> 
> 

Reviewed-by: Fam Zheng <famz@redhat.com>