Injected SessionContext became invalid after passivation

I have SFSB with SessionContext injected as:

@Resource
private SessionContext ctx;

Some of my SFSB's methods use ctx.getBusinessObject(). After passivation and activation of bean ctx.getBusinessObject() produces NPE.
While debugging I discover that ctx is instance of org.jboss.ejb3.BaseSessionContext. In it's writeExternal() / readExternal() it loose baseContext, which is needed for getBusinessObject() invocation.