CVE-2024-35988 is a vulnerability identified in the Linux kernel specifically affecting the RISC-V architecture on 64-bit systems without a Memory Management Unit (NOMMU). The issue arises from an incorrect definition of TASK_SIZE, which is a kernel constant defining the maximum size of the user space memory area. On NOMMU systems, user space memory can be mapped anywhere in physical RAM. However, the existing TASK_SIZE definition does not correctly account for physical RAM located above the 4GB boundary. This misconfiguration leads to spurious failures in userspace memory access routines, potentially causing incorrect behavior or denial of service conditions when the kernel attempts to access user space memory beyond the 4GB threshold. The vulnerability is rooted in the kernel's memory management assumptions for NOMMU RISC-V systems and has been addressed by correcting the TASK_SIZE definition to properly reflect the physical memory layout. No known exploits are currently reported in the wild, and the vulnerability was published on May 20, 2024. The affected versions correspond to specific Linux kernel commits prior to the fix. This vulnerability is technical and specific to a niche architecture and configuration (RISC-V 64-bit NOMMU), which limits its exposure but still poses risks to affected systems.

For European organizations, the impact of CVE-2024-35988 is primarily relevant to those deploying Linux on RISC-V 64-bit NOMMU platforms. Such platforms are typically found in embedded systems, specialized industrial devices, or experimental computing environments rather than mainstream enterprise servers or desktops. The incorrect TASK_SIZE definition can cause failures in user space memory access, potentially leading to application crashes or system instability. This may result in denial of service conditions, impacting availability of critical systems. Confidentiality and integrity impacts are less likely since the vulnerability does not directly enable privilege escalation or arbitrary code execution. However, system instability in critical embedded or industrial control systems could indirectly affect operational continuity. European organizations involved in sectors like manufacturing, telecommunications, or research using RISC-V NOMMU devices should be particularly attentive. The limited market penetration of RISC-V NOMMU Linux systems in Europe reduces the broad impact, but targeted deployments in strategic sectors could face operational disruptions if unpatched.

1. Immediate application of the official Linux kernel patch that corrects the TASK_SIZE definition for RISC-V 64-bit NOMMU systems is essential. Organizations should track kernel updates and apply them promptly. 2. For embedded or industrial devices running affected Linux versions, coordinate with hardware and software vendors to ensure firmware and kernel updates are available and deployed. 3. Conduct an inventory of all RISC-V NOMMU Linux systems within the organization to identify potentially vulnerable devices. 4. Implement monitoring for system stability and unusual application crashes that could indicate exploitation or manifestation of the vulnerability. 5. Where possible, consider architectural changes to avoid NOMMU configurations or migrate to supported architectures with MMU, reducing exposure to this and similar vulnerabilities. 6. For critical systems, establish fallback and recovery procedures to minimize downtime in case of failures caused by this vulnerability. 7. Engage with RISC-V and Linux community resources to stay informed about further developments or related vulnerabilities.