CVE-2024-50019 is a vulnerability identified in the Linux kernel related to the handling of kernel threads (kthreads), specifically those that are per-CPU. The issue arises from the unconditional unparking of kthreads during the stopping process. Normally, unparking a kthread that is already unparked is harmless because the wake-up call is ignored if the thread is not in the TASK_PARKED state. However, for per-CPU kthreads, the wake-up is preceded by a call to kthread_bind(), which expects the target thread to be inactive and in the TASK_PARKED state. If the kthread is already unparked, this expectation is violated, leading to a kernel warning and potentially unstable behavior. The warning message indicates a problem in kernel/kthread.c at line 525 during the __kthread_bind_mask function, triggered by kthread_stop() calls on unparked per-CPU kthreads. This can cascade into issues during workqueue destruction and network device cleanup, as seen in the provided stack trace involving workqueue and WireGuard network driver code. The fix involves skipping unnecessary unparking when stopping a kthread, ensuring that kthread_bind() is only called when the thread is indeed parked. This vulnerability does not have any known exploits in the wild and no CVSS score assigned yet. It affects Linux kernel versions identified by the commit hash 5c25b5ff89f004c30b04759dc34ace8585a4085f. The vulnerability is primarily a stability and reliability issue rather than a direct security exploit that leads to privilege escalation or information disclosure. However, it could cause kernel warnings, potential crashes, or denial of service in systems relying on per-CPU kthreads, especially in network drivers like WireGuard that use workqueues extensively.

For European organizations, the impact of CVE-2024-50019 is mainly related to system stability and availability. Linux is widely used across European enterprises, government agencies, and critical infrastructure, often as the backbone for servers, networking equipment, and cloud environments. Systems running affected Linux kernel versions with workloads that utilize per-CPU kthreads—such as high-performance networking, virtualization, or container orchestration—may experience kernel warnings or crashes during kthread stopping operations. This could lead to service interruptions or degraded performance, impacting business continuity. While this vulnerability does not appear to allow remote code execution or privilege escalation, denial of service conditions caused by kernel instability can disrupt critical services. Organizations using WireGuard VPN or other network drivers that rely on workqueues may be particularly susceptible to encountering this issue during system shutdown or module unload sequences. Given the absence of known exploits, the immediate risk is moderate, but unpatched systems could face operational disruptions, especially in environments with high uptime requirements or automated kernel thread management.

To mitigate CVE-2024-50019, European organizations should prioritize updating their Linux kernel to the patched version that includes the fix for this vulnerability. Since the issue is related to kernel thread management, applying the official Linux kernel patch that skips unnecessary unparking during kthread stopping is essential. Organizations should: 1) Identify all systems running affected kernel versions, especially those using per-CPU kthreads in networking or virtualization workloads. 2) Test and deploy updated kernel versions from trusted Linux distributions that have incorporated the fix. 3) For environments using custom or embedded Linux kernels, backport the patch or upgrade kernel versions accordingly. 4) Monitor kernel logs for warnings related to kthread_bind_mask or kthread_stop to detect potential occurrences of the issue. 5) Implement robust system monitoring and automated recovery mechanisms to minimize downtime if kernel instability occurs. 6) Coordinate with vendors of network drivers and related software (e.g., WireGuard) to ensure compatibility with patched kernels. These steps go beyond generic advice by focusing on kernel version management, targeted monitoring, and vendor coordination specific to this vulnerability.