chipsalliance/rocket-chip

A vulnerability was discovered in RISC-V Rocket-Chip v1.6 and before implementation where the SRET (Supervisor-mode Exception Return) instruction fails to correctly transition the processor's privilege level. Instead of downgrading from Machine-mode (M-mode) to Supervisor-mode (S-mode) as specified by the sstatus.SPP bit, the processor incorrectly remains in M-mode, leading to a critical privilege retention vulnerability.

An issue was discovered in Chipsalliance Rocket-Chip commit f517abbf41abb65cea37421d3559f9739efd00a9 (2025-01-29) allowing attackers to corrupt exception handling and privilege state transitions via a flawed interaction between exception handling and MRET return mechanisms in the CSR logic when an exception is triggered during MRET execution. The Control and Status Register (CSR) logic has a flawed interaction between exception handling and exception return (MRET) mechanisms which can cause faulty trap behavior. When the MRET instruction is executed in machine mode without being in an exception state, an Instruction Access Fault may be triggered. This results in both the exception handling logic and the exception return logic activating simultaneously, leading to conflicting updates to the control and status registers.

Improper mstatus.SUM bit retention (non-zero) in Open-Source RISC-V Processor commit f517abb violates privileged spec constraints, enabling potential physical memory access attacks.

Rocket-Chip commit 4f8114374d8824dfdec03f576a8cd68bebce4e56 was discovered to contain insufficient cryptography via the component /rocket/RocketCore.scala.