Conclusion

SP1's implementation of aliasing registers with low memory addresses (0x0-0x1f) is an interesting implementation decision. Technically, reserved memory ranges are not incompatible with the RISC-V specification, which explicitly provides affordances for implementers to define them, nor are the effects of undefined behavior. Nonetheless, while this is not a security vulnerability in itself, we recommend implementing instruction-level checks to ignore operations to these low memory addresses to strengthen SP1's security posture and reduce potential attack surface for vulnerable programs. Furthermore, we recommend Succinct document and standardize this, rather than leave it as undefined behavior.