Denial-of-Service Attacks on Shared Cache in Multicore: Analysis and Prevention

Abstract

In this paper we investigate the feasibility of denialof-service (DoS) attacks on shared caches in multicore platforms. With carefully engineered attacker tasks, we are able to cause more than 300X execution time increases on a victim task running on a dedicated core on a popular embedded multicore platform, regardless of whether we partition its shared cache or not. Based on careful experimentation on real and simulated multicore platforms, we identify an internal hardware structure of a nonblocking cache, namely the cache writeback buffer, as a potential target of shared cache DoS attacks. We propose an OS-level solution to prevent such DoS attacks by extending a state-of-theart memory bandwidth regulation mechanism. We implement the proposed mechanism in Linux on a real multicore platform and show its effectiveness in protecting against cache DoS attacks.

RT-Gang: Real-Time Gang Scheduling Framework for Safety-Critical Systems

“…For example, we observed more than 100X slowdown (two orders of magnitudes) using a linked-list iteration task on the same computing platform used above, even after we partition core as well as the shared cache among the tasks. Similar degrees of timing impacts of interference have been reported in recent empirical studies on contemporary embedded multicore platforms [7], [8], [51], [52], [57].…”

“…While these shared resource partitioning techniques can reduce space conflicts of some shared resources, hence beneficial for predictability, but they are not enough to guarantee strong time predictability on COTS multicore platforms because there are too many hardware resources (e.g., cache MSHRs, DRAM controller buffers, etc.) that have profound impact on task timing [8], [51], but are unpartitionable and out of control of software.…”

Slow and Steady: Measuring and Tuning Multicore Interference

“…As in prior work [24], [3], we are interested in evaluating commodity hardware using a regular (i.e. non-real-time) operating system, as this is a realistic usage scenario for early evaluation of COTS processors.…”

“…We attempted to reproduce the highest slowdowns reported in recent interference work by Bechtel and Yun [3]: namely, that their BwWrite enemy program can cause a slowdown of more than 300× on a synthetic memory-intensive piece of software (on a Raspberry Pi 3 B chip). The architectural intuition behind these results is that the BwWrite program exploits the internal structure of non-blocking shared caches by filling the miss-status holding register and write-back buffer.…”

“…The key idea is to design enemy programs that access shared resources in just the right way to maximise the contention with a program running on another core [24], [21], [12]. Prior work has designed several enemy programs, demonstrating substantial slowdowns on commercial off-the-shelf (COTS) processors of more than 300× [3].…”