CVE-2023-52940 is a vulnerability in the Linux kernel related to the multi-generation Least Recently Used (multi-gen LRU) memory management subsystem. Specifically, the issue arises in the function lru_gen_migrate_mm(), which assumes that lru_gen_add_mm() has already been executed prior to its invocation. However, under certain concurrent execution scenarios involving CPU cores, this assumption does not hold true. The described scenario involves a race condition between two CPUs during process cloning and cgroup migration operations. CPU 1 executes clone(), cgroup_can_fork(), and cgroup_post_fork(), while CPU 2 concurrently performs cgroup_procs_write(), task_lock(), lru_gen_migrate_mm(), and task_unlock(). The interleaving of these operations causes lru_gen_migrate_mm() to run before lru_gen_add_mm(), leading to corruption of the linked list mm_struct->lru_gen.list. This linked list corruption results in kernel crashes, causing system instability or denial of service. The vulnerability affects specific Linux kernel versions identified by commit hashes bd74fdaea146029e4fa12c6de89adbe0779348a9. No known exploits are currently reported in the wild, and no CVSS score has been assigned. The root cause is a race condition in kernel memory management during cgroup migration, highlighting a concurrency flaw in the kernel's handling of memory management data structures during process lifecycle events.

For European organizations, this vulnerability poses a risk primarily to systems running affected Linux kernel versions, especially those utilizing cgroups for resource management and container orchestration. The kernel crash caused by linked list corruption can lead to system instability and denial of service, impacting availability of critical services. Organizations relying on Linux-based servers, cloud infrastructure, or container platforms (e.g., Kubernetes) could experience outages or degraded performance. In sectors such as finance, healthcare, telecommunications, and government, where Linux servers are prevalent, such disruptions could affect business continuity and service delivery. Although no known exploits exist yet, the vulnerability's nature as a kernel crash-inducing race condition means that attackers with local access or the ability to trigger cgroup migrations could cause denial of service. This could be leveraged in multi-tenant environments or shared infrastructure common in European data centers. The impact on confidentiality and integrity is limited, as the vulnerability does not directly enable privilege escalation or data leakage, but availability impact is significant.

To mitigate CVE-2023-52940, European organizations should: 1) Apply the latest Linux kernel patches that address this vulnerability as soon as they become available, ensuring that affected kernel versions are upgraded or backported fixes are applied. 2) Monitor and control access to systems with the ability to perform cgroup migrations or process cloning, limiting such operations to trusted users and processes to reduce risk of exploitation. 3) In containerized environments, carefully manage cgroup configurations and consider isolating critical workloads to minimize the impact of potential kernel crashes. 4) Implement robust system monitoring and alerting for kernel crashes and unusual cgroup activity to detect exploitation attempts early. 5) Conduct thorough testing of kernel updates in staging environments to ensure stability before deployment in production. 6) Employ defense-in-depth strategies such as SELinux or AppArmor to restrict process capabilities and reduce attack surface related to cgroup operations. 7) Maintain comprehensive backups and disaster recovery plans to quickly restore services in case of denial of service incidents caused by this vulnerability.