CVE-2024-42073 is a vulnerability identified in the Linux kernel specifically affecting the mlxsw driver used for managing Spectrum-4 network switch systems. The issue arises from improper handling of the Shared Buffer Status Register (SBSR), which is used by two shared buffer operations: 'devlink sb occupancy snapshot' and 'devlink sb occupancy clearmax'. The SBSR register contains two 256-bit masks to indicate ingress and egress ports for operation. However, Spectrum-4 systems support more than 256 ports, requiring an extension of the register with a 'port_page' field to segment ports into pages. The vulnerability occurs because the driver incorrectly specifies ports as absolute numbers rather than relative to the first port of the port page when filling the register's payload. This miscalculation leads to memory corruption, specifically a use-after-free condition detected by Kernel Address Sanitizer (KASAN), which can cause kernel crashes or unpredictable behavior. The detailed kernel stack trace shows that the corruption happens during the execution of devlink commands interacting with the shared buffer occupancy snapshot functionality, potentially triggered by user-space processes with access to devlink interfaces. The root cause is a logic error in port indexing within the mlxsw_sp_sb_occ_snapshot function, fixed by adjusting port references to be relative to the port page base. This vulnerability affects Linux kernel versions containing the faulty mlxsw driver code prior to the patch and is relevant for systems running Spectrum-4 switches. No known exploits are reported in the wild as of the publication date, and no CVSS score has been assigned yet.

For European organizations, this vulnerability poses a risk primarily to data centers, telecommunications providers, and enterprises using Linux-based Spectrum-4 network switches for high-performance networking infrastructure. Exploitation could lead to kernel memory corruption resulting in denial of service (system crashes or reboots) or potentially enable privilege escalation or arbitrary code execution within the kernel context if combined with other vulnerabilities. This could disrupt critical network services, degrade performance, or cause outages impacting business operations. Confidentiality and integrity impacts are possible if attackers leverage the memory corruption to execute malicious code or access sensitive kernel memory. Given the specialized nature of the hardware (Spectrum-4 switches) and the requirement for access to devlink interfaces, the threat is more relevant to organizations with advanced networking setups rather than general desktop or server Linux users. However, the widespread use of Linux in European enterprise and telecom environments means that the vulnerability could affect a significant number of critical infrastructure deployments if unpatched.

1. Immediate application of the official Linux kernel patches that correct the port indexing logic in the mlxsw driver is essential. Organizations should track Linux kernel updates and deploy security patches promptly on all affected systems running Spectrum-4 switches. 2. Restrict access to devlink interfaces to trusted administrators only, minimizing the risk of unauthorized triggering of the vulnerable operations. 3. Implement kernel runtime security monitoring tools capable of detecting anomalous kernel memory corruption or crashes to provide early warning of exploitation attempts. 4. Conduct thorough testing of network switch firmware and Linux kernel updates in staging environments before production deployment to avoid service disruptions. 5. For organizations using Spectrum-4 switches in virtualized or containerized environments, ensure that kernel namespaces and access controls are properly configured to limit exposure. 6. Maintain up-to-date inventories of hardware and software to quickly identify systems running vulnerable kernel versions and affected drivers. 7. Engage with hardware vendors and Linux distribution maintainers for coordinated vulnerability disclosure and patch management.