CVE-2024-56592 is a vulnerability identified in the Linux kernel's Berkeley Packet Filter (BPF) subsystem, specifically related to the handling of hash table (htab) elements within BPF maps. The issue arises from improper lock management during the removal and freeing of map elements. When a map is removed from the htab, it may hold the last reference to that map. The function bpf_map_fd_put_ptr() is responsible for freeing the map's ID by invoking bpf_map_free_id(). However, this function is called while holding a bucket lock (raw_spin_lock_t), and bpf_map_free_id() attempts to acquire another lock (map_idr_lock), leading to a lock dependency (lockdep) warning and an invalid wait context bug. This improper locking sequence can cause kernel warnings and potentially lead to deadlocks or race conditions. The root cause is that freeing operations are performed while holding locks that conflict with other locks acquired inside the freeing functions. The fix involves deferring the invocation of freeing functions such as htab_put_fd_value() and free_htab_elem() until after the bucket lock is released. This deferral ensures that locks are not nested in a problematic order, preventing lockdep warnings and invalid wait contexts. The patch also includes careful handling of old map pointers and special fields in the htab elements to avoid premature freeing or reuse issues during batched deletions. The vulnerability affects Linux kernel versions around 6.11.0-rc4+ and involves complex interactions between spinlocks and raw spinlocks in the BPF map management code. No known exploits are reported in the wild at this time, and no CVSS score has been assigned yet.

For European organizations, this vulnerability primarily threatens the stability and reliability of Linux-based systems that utilize BPF maps extensively, such as those running container orchestration platforms (e.g., Kubernetes), network monitoring tools, or security appliances leveraging eBPF for packet filtering and tracing. The improper lock handling can lead to kernel warnings, potential deadlocks, or race conditions that may cause system crashes or degraded performance. This can result in denial of service (DoS) conditions, impacting critical infrastructure, cloud services, and enterprise environments relying on Linux servers. While the vulnerability does not directly expose confidentiality or integrity risks, the availability impact can be significant, especially in high-availability or real-time systems. Since BPF is widely used for advanced networking and security functions, any instability can disrupt network traffic analysis, firewalling, or observability tools, affecting incident response and operational continuity. The absence of known exploits suggests that exploitation complexity is non-trivial, but the risk remains for sophisticated attackers or accidental system failures triggered by this bug.

European organizations should prioritize updating their Linux kernels to versions where this vulnerability is patched, particularly those using kernel versions around 6.11.0-rc4 or similar development releases. System administrators should: 1) Apply official Linux kernel patches addressing CVE-2024-56592 as soon as they become available from trusted sources or distributions. 2) Monitor kernel logs for lockdep warnings or invalid wait context messages that may indicate attempts to trigger this issue or system instability. 3) Limit the use of untrusted or experimental BPF programs that heavily manipulate htab maps until patches are applied. 4) Employ kernel live patching solutions where feasible to reduce downtime during updates. 5) Conduct thorough testing of critical systems after patching to ensure stability and performance are maintained. 6) Implement robust monitoring and alerting on kernel-level errors to detect early signs of exploitation or system faults related to this vulnerability. 7) Collaborate with Linux distribution vendors to receive timely updates and security advisories. These steps go beyond generic advice by focusing on kernel version management, proactive monitoring of kernel lock warnings, and cautious deployment of BPF programs.