qcow2: fix encryption during cow of sectors

Broken in previous commit:

  commit aaa4d20b4972bb1a811ce929502e6741835d584e
  Author: Kevin Wolf <kwolf@redhat.com>
  Date:   Wed Jun 1 15:21:05 2016 +0200

      qcow2: Make copy_sectors() byte based

The copy_sectors() code was originally using the 'sector'
parameter for encryption, which was passed in by the caller
from the QCowL2Meta.offset field (aka the guest logical
offset).

After the change, the code is using 'cluster_offset' which
was passed in from QCow2L2Meta.alloc_offset field (aka the
host physical offset).

This would cause the data to be encrypted using an incorrect
initialization vector which will in turn cause later reads
to return garbage.

Although current qcow2 built-in encryption is blocked from
usage in the emulator, one could still hit this if writing
to the file via qemu-{img,io,nbd} commands.

Cc: qemu-stable@nongnu.org
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 9ab445dd17..61d1ffd223 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -429,7 +429,7 @@ static int coroutine_fn do_perform_cow(BlockDriverState *bs,
 
     if (bs->encrypted) {
         Error *err = NULL;
-        int64_t sector = (cluster_offset + offset_in_cluster)
+        int64_t sector = (src_cluster_offset + offset_in_cluster)
                          >> BDRV_SECTOR_BITS;
         assert(s->cipher);
         assert((offset_in_cluster & ~BDRV_SECTOR_MASK) == 0);