Commit 5c0ba1be authored by Felipe Franciosi's avatar Felipe Franciosi Committed by Michael S. Tsirkin
Browse files

virtio/vhost: reset dev->log after syncing 



vhost_log_put() is called to decomission the dirty log between qemu and
a vhost device when stopping the device. Such a call can happen from
migration_completion().

Present code sets dev->log_size to zero too early in vhost_log_put(),
causing the sync check to always return false. As a consequence, the
last pass on the dirty bitmap never happens at the end of migration.

If a vhost device was busy (writing to guest memory) until the last
moments before vhost_virtqueue_stop(), this error will result in guest
memory corruption (at least) following migrations.

Signed-off-by: default avatarFelipe Franciosi <felipe@nutanix.com>
Acked-by: default avatarJason Wang <jasowang@redhat.com>
Reviewed-by: default avatarMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 3505a22b

hw/virtio/vhost.c

+3 −2
Original line number Diff line number Diff line
@@ -375,8 +375,6 @@ static void vhost_log_put(struct vhost_dev *dev, bool sync) 
    if (!log) {

        return;

    }

    dev->log = NULL;

    dev->log_size = 0;



    --log->refcnt;

    if (log->refcnt == 0) {
@@ -396,6 +394,9 @@ static void vhost_log_put(struct vhost_dev *dev, bool sync) 


        g_free(log);

    }



    dev->log = NULL;

    dev->log_size = 0;

}



static bool vhost_dev_log_is_shared(struct vhost_dev *dev)