Salaried employees are paid a salary. It's a flat amount regardless of hours worked. Are you expecting to get bonus money for hours over 40? Are you willing to pay back some to your employer for hours worked under 40? Then go work an hourly job.
You can not be made to work without your salary being paid at all, but you can be made to work more than 40 hours without additional compensation. You accept that this is a possibility when you agree to work for a flat salary.