Fix missing offset verification.
Cc: qemu-stable@nongnu.org
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Reported-by: Qiuhao Li <Qiuhao.Li@outlook.com>
Fixes: f432fdfa12
("support changed namespace asynchronous event")
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Klaus Jensen <k.jensen@samsung.com>