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[Qemu-devel] [PATCH v3 1/1] block/vmdk: Fix the endian problem of buf_le

From: QingFeng Hao
Subject: [Qemu-devel] [PATCH v3 1/1] block/vmdk: Fix the endian problem of buf_len and lba
Date: Fri, 16 Dec 2016 06:20:40 +0100

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: address@hidden
Signed-off-by: QingFeng Hao <address@hidden>
Signed-off-by: Jing Liu <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
Reviewed-by: Fam Zheng <address@hidden>
 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 
             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) {

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