CVE-2022-34641 in CVA6
Summary
by MITRE • 07/19/2022
CVA6 commit d315ddd0f1be27c1b3f27eb0b8daf471a952299a and RISCV-Boom commit ad64c5419151e5e886daee7084d8399713b46b4b implements the incorrect exception type when a PMP violation occurs during address translation.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 08/06/2022
The vulnerability identified as CVE-2022-34641 affects the CVA6 and RISCV-Boom processor implementations within the RISC-V architecture ecosystem. This flaw manifests in the incorrect handling of exception types during memory access violations that occur while performing address translation operations. The issue stems from the improper classification of exceptions when Privileged Memory Protection (PMP) rules are violated during the address translation process, creating a potential security risk that could be exploited by malicious actors. The vulnerability is particularly concerning because it affects the fundamental memory management mechanisms that govern how processors handle memory access permissions and address translation operations.
The technical flaw lies in the exception handling mechanism where the processor fails to correctly identify and categorize the type of exception that should be generated when a PMP violation occurs during address translation. In proper implementations, when memory access violates PMP constraints, the processor should generate a specific exception type that accurately reflects the nature of the violation. However, in this case, the processor incorrectly assigns exception types that do not properly represent the actual memory protection violation that occurred. This misclassification can lead to improper handling of memory access attempts and potentially allow unauthorized memory access that should have been blocked by the PMP mechanism. The vulnerability is rooted in the processor's memory management unit implementation and how it interacts with the address translation logic during memory access operations.
The operational impact of this vulnerability extends beyond simple memory access control failures and can potentially compromise the entire system security posture. When PMP violations are incorrectly handled during address translation, it may allow attackers to bypass memory protection mechanisms that are designed to prevent unauthorized access to sensitive memory regions. This could enable privilege escalation attacks, data leakage, or the execution of unauthorized code in protected memory spaces. The vulnerability affects both CVA6 and RISCV-Boom implementations, suggesting a widespread impact across various RISC-V processor designs that rely on similar memory management approaches. The improper exception handling could also lead to system instability or unexpected behavior during normal operation, as the processor's memory management unit fails to properly enforce access controls.
Mitigation strategies for this vulnerability require immediate updates to the affected processor implementations through firmware or hardware updates that correct the exception type handling during PMP violations. System administrators should prioritize patching affected systems to ensure that the correct exception types are generated when PMP violations occur during address translation. The fix should involve modifying the memory management unit logic to properly classify and handle PMP violation exceptions according to established RISC-V specifications. Additionally, organizations should implement monitoring systems to detect any anomalous memory access patterns that might indicate exploitation attempts. This vulnerability aligns with CWE-119 which addresses memory safety issues and could be categorized under ATT&CK technique T1068 for local privilege escalation, making it a critical security concern for any system utilizing affected RISC-V processor implementations.