Re: [Qemu-devel] [PATCH v2 1/1] block/vmdk: Fix the endian problem of buf_len and lba

[liujing <liujbjl@linux.vnet.ibm.com>]

Hi QingFeng,


I just have a question that whether the marker->data
need convert?

I've no idea, just suddenly realized this question.

Jing

On 11/26/2016 01:46 PM, QingFeng Hao wrote:
> The problem was triggered by qemu-iotests case 055. It failed when it
> was comparing the compressed vmdk image with original test.img.
>
> The cause is that buf_len in vmdk_write_extent wasn't converted to
> little-endian before it was stored to disk. But later vmdk_read_extent
> read it and converted it from little-endian to cpu endian.
> If the cpu is big-endian like s390, the problem will happen and
> the data length read by vmdk_read_extent will become invalid!
> The fix is to add the conversion in vmdk_write_extent, meanwhile,
> repair the endianness problem of lba field which shall also be converted
> to little-endian before storing to disk.
>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: QingFeng Hao <haoqf@linux.vnet.ibm.com>
> Signed-off-by: Jing Liu <liujbjl@linux.vnet.ibm.com>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   block/vmdk.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/block/vmdk.c b/block/vmdk.c
> index a11c27a..26e5f95 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -1354,8 +1354,8 @@ static int vmdk_write_extent(VmdkExtent *extent, int64_t cluster_offset,
>               goto out;
>           }
>
> -        data->lba = offset >> BDRV_SECTOR_BITS;
> -        data->size = buf_len;
> +        data->lba = cpu_to_le64(offset >> BDRV_SECTOR_BITS);
> +        data->size = cpu_to_le32(buf_len);
>
>           n_bytes = buf_len + sizeof(VmdkGrainMarker);
>           iov = (struct iovec) {