Work-in-Progress: RWS - A Roulette Wheel Scheduler for Preventing Execution Pattern Leakage

Ying Zhang, Lingxiang Wang, Wei Jiang, Zhishan Guo

Abstract: Many real-time systems are safety-critical, where reliability is crucial. Under traditional scheduling mechanism, the execution patterns of the tasks on such system can be easily derived from side-channel attacks, such that attackers can launch short high-priority tasks at critical instants which may cause deadline miss for high-critical tasks. In order to protect the system from such kind of attacks, this paper proposes the roulette wheel scheduler (RWS) to randomize the task execution pattern. Under RWS, probabilities will be assigned to each task at predefined scheduling points, and the choice for execution is randomized, such that the execution pattern is no longer fixed. We formalize the concept of schedule entropy the additional safety provided by any randomized scheduler. It is used to measure the amount of uncertainty introduced by the new scheduler.