CVE-2025-37940 addresses a performance-related vulnerability in the Linux kernel's ftrace subsystem, specifically within the function ftrace_graph_set_hash(). Ftrace is a kernel feature used for tracing and debugging kernel functions. The vulnerability arises when the kernel contains a large number of traceable functions, causing the loop inside ftrace_graph_set_hash() to execute for an extended period. This prolonged execution can trigger the kernel's softlockup watchdog, a mechanism designed to detect and recover from kernel hangs or stalls. The root cause is the absence of a conditional reschedule call (cond_resched()) within this loop, which would allow the kernel scheduler to preempt the current task and maintain system responsiveness. The patch introduces cond_resched() calls inside the loop, aligning with existing practices in similar kernel code paths that iterate over traceable functions. This change prevents the kernel from becoming unresponsive during extensive tracing operations by allowing other processes to run, thus mitigating the risk of softlockups caused by this function. The vulnerability does not appear to be exploitable for privilege escalation or code execution but can lead to denial of service through system unresponsiveness under specific workloads involving heavy kernel tracing.

For European organizations, the primary impact of this vulnerability is on system stability and availability, particularly in environments that utilize kernel tracing extensively for debugging, performance monitoring, or security auditing. Systems running affected Linux kernel versions with heavy use of ftrace may experience softlockups, leading to temporary system hangs or degraded performance. This can affect critical infrastructure, data centers, and cloud services that rely on Linux servers, potentially causing service interruptions. Industries such as telecommunications, finance, manufacturing, and public sector entities that depend on Linux-based systems for operational continuity may face operational disruptions. However, since this vulnerability does not enable remote code execution or privilege escalation, the confidentiality and integrity of data are not directly at risk. The impact is primarily on availability and system responsiveness, which can still have significant operational consequences in high-availability environments.

To mitigate this vulnerability, organizations should prioritize updating their Linux kernel to the patched version that includes the cond_resched() addition in ftrace_graph_set_hash(). Kernel updates should be tested and deployed promptly, especially on systems that perform extensive kernel tracing. For environments where immediate patching is not feasible, administrators should limit or avoid heavy use of ftrace tracing features that could trigger the softlockup condition. Monitoring system logs and kernel watchdog alerts can help detect early signs of softlockups. Additionally, implementing robust system monitoring and automated recovery mechanisms can reduce downtime if a softlockup occurs. Organizations should also review their kernel tracing configurations and consider alternative debugging tools that do not induce long-running kernel loops. Collaboration with Linux distribution vendors for timely patches and guidance is recommended to ensure comprehensive protection.