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

[Hao QingFeng <haoqf@linux.vnet.ibm.com>]

在 2016-11-28 15:56, liujing 写道:
> Hi QingFeng,
>
>
> I just have a question that whether the marker->data
> need convert?
>
> I've no idea, just suddenly realized this question.
>
nope, the data is type of char * for the compressed data stream, so no 
endian issue.
thanks.
> 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) {
>

-- 
QingFeng Hao(Robin)