CVE-2024-35998 is a vulnerability identified in the Linux kernel's SMB3 (Server Message Block version 3) implementation, specifically within the cifs_sync_mid_result function. The issue arises from a potential deadlock caused by improper lock ordering. According to the analysis by Coverity, a static analysis tool, the function acquires the spin_lock on TCP_Server_Info.srv_lock while already holding the lock on TCP_Server_Info.mid_lock, leading to a lock order reversal scenario. This lock ordering flaw can cause threads to deadlock, where two or more threads wait indefinitely for locks held by each other, effectively halting progress in the affected kernel subsystem. The vulnerability is related to the CIFS (Common Internet File System) client implementation in the Linux kernel, which is used to interact with SMB shares. The deadlock can impact the kernel's ability to process SMB3 requests, potentially causing system hangs or degraded performance. The vulnerability was detected and fixed promptly, with patches integrated into the Linux kernel source. No known exploits are currently reported in the wild, and the vulnerability does not have an assigned CVSS score. The affected versions are identified by specific kernel commit hashes, indicating that the issue is present in certain recent kernel builds prior to the fix. This vulnerability is primarily a denial-of-service (DoS) risk due to the potential for deadlock, rather than a direct code execution or privilege escalation flaw.

For European organizations, the primary impact of CVE-2024-35998 is the risk of denial-of-service conditions on Linux systems that utilize the CIFS/SMB3 client functionality, especially those that mount SMB shares from Windows or Samba servers. This can affect file sharing services, network-attached storage access, and any applications relying on SMB3 communication. In environments with high SMB traffic, such as enterprises with mixed Windows-Linux infrastructure, the deadlock could lead to system instability or unresponsiveness, impacting business continuity. Critical infrastructure, cloud providers, and data centers running Linux servers with SMB3 mounts may experience service interruptions. While the vulnerability does not directly expose data confidentiality or integrity risks, the availability impact can be significant, particularly for organizations with stringent uptime requirements. The absence of known exploits reduces immediate risk, but the vulnerability should be addressed proactively to prevent potential future exploitation or accidental system hangs. Given the widespread use of Linux in European public and private sectors, especially in government, finance, and telecommunications, the vulnerability's impact on availability is a concern that must be mitigated.

To mitigate CVE-2024-35998, European organizations should: 1) Apply the latest Linux kernel patches that address the lock ordering issue in the SMB3 CIFS client code as soon as they become available from trusted sources or Linux distribution vendors. 2) For environments where immediate patching is not feasible, consider temporarily disabling SMB3 mounts or CIFS client usage on critical systems to avoid triggering the deadlock condition. 3) Monitor system logs and kernel messages for signs of deadlock or hangs related to CIFS/SMB3 operations, enabling early detection of issues. 4) Implement robust system monitoring and alerting to detect unresponsive states potentially caused by this vulnerability. 5) Review and limit SMB3 usage to necessary systems only, reducing the attack surface and exposure. 6) Coordinate with network and storage teams to ensure alternative file sharing methods or redundancy are in place to maintain availability during patch deployment. 7) Engage with Linux distribution security advisories and subscribe to vulnerability notifications to stay informed about updates and related issues. These steps go beyond generic advice by focusing on operational controls, monitoring, and coordination specific to SMB3 CIFS client usage in Linux environments.