CVE-2022-49640 is a concurrency-related vulnerability in the Linux kernel affecting the sysctl interface, specifically within the proc_douintvec_minmax() function. This function handles sysctl variables that are accessed concurrently by multiple readers and writers without adequate synchronization, leading to potential data races. A data race occurs when two or more threads access the same memory location concurrently, and at least one of the accesses is a write, without proper synchronization mechanisms. This can cause inconsistent or corrupted data reads and writes, potentially leading to unpredictable kernel behavior or system instability. The vulnerability arises because proc_douintvec_minmax() did not use atomic access primitives, allowing load/store tearing and race conditions on sysctl variables. The fix involves modifying proc_douintvec_minmax() to use READ_ONCE() and WRITE_ONCE() macros, which ensure atomic reads and writes to the variables, preventing torn or partial accesses and eliminating the data race on the sysctl side. Although proc_douintvec_minmax() itself is now tolerant to data races, further annotations and protections are needed on other subsystems that interact with these variables to fully mitigate race conditions. This vulnerability is rooted in kernel-level concurrency management and affects Linux kernel versions identified by the provided commit hashes. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The issue is primarily a reliability and integrity concern within the kernel's sysctl interface, which is critical for system configuration and runtime parameter tuning.

For European organizations, the impact of CVE-2022-49640 depends on their reliance on Linux-based systems, especially those running kernel versions prior to the patch. The vulnerability could lead to kernel data corruption or instability due to race conditions in sysctl variable access, potentially causing system crashes or unpredictable behavior. This can affect servers, network infrastructure, and embedded devices running Linux, leading to downtime or degraded service availability. While there is no direct evidence that this vulnerability allows privilege escalation or remote code execution, kernel instability can be exploited as a stepping stone in complex attack chains. Organizations with critical infrastructure, cloud services, or industrial control systems running Linux kernels vulnerable to this issue may face operational risks. Additionally, the lack of authentication or user interaction requirements for sysctl access in some contexts could increase the attack surface if local unprivileged users can trigger the race condition. However, since no known exploits exist in the wild, the immediate threat level is moderate, but the potential for future exploitation remains if attackers develop techniques to leverage this race condition.

European organizations should prioritize updating their Linux kernels to versions that include the patch fixing CVE-2022-49640. Specifically, they should apply kernel updates that incorporate the use of READ_ONCE() and WRITE_ONCE() in proc_douintvec_minmax() and related subsystems. System administrators should audit their environments to identify Linux systems running vulnerable kernel versions and schedule timely patch deployments. For environments where immediate patching is not feasible, organizations should restrict access to sysctl interfaces to trusted users only, minimizing the risk of local exploitation. Additionally, monitoring kernel logs and system behavior for anomalies or crashes related to sysctl access can help detect attempts to trigger the race condition. Developers maintaining custom kernel modules or subsystems interacting with sysctl variables should review their code for proper synchronization and consider adding similar atomic access annotations to prevent related data races. Finally, organizations should maintain robust backup and recovery procedures to mitigate potential downtime caused by kernel instability.