CVE-2024-35793 is a vulnerability identified in the Linux kernel's debugfs subsystem, specifically related to the handling of wait and cancellation logic during the removal of debugfs entries. Debugfs is a special filesystem used primarily for debugging purposes, allowing kernel developers and administrators to expose kernel information and control interfaces. The vulnerability arises from incorrect logic in the cancellation and reference counting mechanism during concurrent removal of debugfs files while they are being accessed. The flawed logic prevents the triggering of necessary cancellation loops when the reference count does not hit zero, which can lead to deadlocks. This means that when multiple processes concurrently access and remove debugfs files, the kernel may enter a deadlock state, causing the affected system to hang or become unresponsive. The issue was discovered and reported by Ben Greear, who highlighted that despite previous code reviews and attempts to handle cancellations properly, the logic was fundamentally incorrect. The fix involves correcting the cancellation triggering logic to ensure that when the reference count is not zero, all cancellations are properly triggered, preventing deadlocks. This vulnerability affects specific Linux kernel versions identified by the commit hash 8c88a474357ead632b07c70bf7f119ace8c3b39e. There are no known exploits in the wild at the time of publication, and no CVSS score has been assigned yet. The vulnerability is technical and low-level, impacting kernel stability and availability rather than confidentiality or integrity directly.

For European organizations, the primary impact of CVE-2024-35793 lies in system availability and stability. Linux is widely used across European enterprises, government agencies, and critical infrastructure, especially in servers, cloud environments, and embedded systems. A deadlock in the kernel due to this vulnerability could cause system hangs or crashes, leading to denial of service conditions. This can disrupt business operations, especially for organizations relying on Linux-based systems for critical applications or services. While the vulnerability does not directly expose sensitive data or allow privilege escalation, the resulting system instability could be exploited by attackers to cause service outages or to mask other malicious activities. Organizations running custom or debug-enabled kernels, or those that utilize debugfs extensively for monitoring and troubleshooting, are at higher risk. The lack of known exploits suggests that the threat is currently theoretical, but the complexity of kernel deadlocks means that even accidental triggering could cause significant operational issues. In sectors such as finance, healthcare, telecommunications, and government, where Linux servers are integral, this could translate into downtime, loss of productivity, and potential regulatory compliance issues related to service availability.

To mitigate CVE-2024-35793, European organizations should: 1) Apply the official Linux kernel patch that corrects the debugfs cancellation and wait handling logic as soon as it becomes available from trusted Linux distribution vendors or the Linux kernel mainline. 2) Monitor kernel updates and subscribe to security advisories from their Linux distribution maintainers to ensure timely patching. 3) Limit or disable the use of debugfs in production environments where it is not strictly necessary, as debugfs is primarily a debugging tool and not required for normal operation. 4) Implement robust system monitoring to detect unusual system hangs or deadlocks that could indicate triggering of this vulnerability. 5) Conduct thorough testing of kernel updates in staging environments before deployment to production to avoid unintended side effects. 6) For environments where debugfs usage is essential, consider isolating critical workloads to minimize the impact of potential deadlocks. 7) Educate system administrators about the risks associated with debugfs and encourage best practices in kernel debugging and maintenance.