MSMPX: Microarchitectural Extensions for Meltdown Safe Memory Protection

In recent years several hardware enforced pointer protection schemes have been proposed. The most notable amongst them is the Intel MPX, which can identify spatial violations at run time. Recently, it is shown that Intel MPX is vulnerable to a potent attack called Meltdown, which exploits the processor's transient behavior during speculative execution.In this paper, we show that there is a fundamental design flaw in Intel MPX and all other hardware enforced pointer protection schemes that we surveyed, making all of them vulnerable to Meltdown. We then suggest a design strategy called MSMPX, that provides hardware enforced pointer protection, while at the same time being immune to Meltdown. We compare the hardware overheads on an OpenRISC processor and the performance overheads with respect to Intel MPX.