International visitors must always have a valid passport and visa. Depending on the country you are from, the rules to apply for passport renewal are available on the consular website. Usually, one may apply for renewal, 6 months prior to expiry. Travel is not permitted with an expired passport or visa.
If the visa is expiring and the student is yet to complete the program of study, the student may request the department for a letter which can be then used to convince the International Student Office to extend the study period on their I20. They will also make the appropriate change in the SEVIS database. After this, the student must make an appointment at the US consulate for the visa extension.