CVE-2024-38385 is a use-after-free vulnerability identified in the Linux kernel's interrupt handling subsystem, specifically within the genirq/irqdesc code. The vulnerability arises in the irq_find_at_or_after() function, which dereferences an interrupt descriptor returned by mt_find() without holding the necessary synchronization mechanisms—namely, neither the sparse_irq_lock nor the RCU (Read-Copy-Update) read lock. This lack of proper locking allows the descriptor to be freed concurrently between the mt_find() call and its dereference, leading to a use-after-free condition. The race condition is demonstrated by concurrent CPU operations where one CPU obtains the descriptor via mt_find(), while another CPU frees the descriptor via delayed_free_desc(). The kernel's KASAN (Kernel Address Sanitizer) tool detected this flaw, providing a call trace that highlights the vulnerable code paths involved in irq_get_next_irq, show_stat, and proc_reg_read_iter, among others. The root cause is the absence of an RCU read lock guarding the access to the interrupt descriptor, which is critical to prevent the descriptor from being freed while still in use. The fix involves wrapping the access to the descriptor within an RCU read lock section to ensure safe concurrent access and prevent use-after-free conditions. This vulnerability affects Linux kernel versions identified by the given commit hashes and was published on June 25, 2024. No known exploits are currently reported in the wild.

For European organizations, this vulnerability poses a risk primarily to systems running vulnerable Linux kernel versions, which are widespread across enterprise servers, cloud infrastructure, and embedded devices. Exploitation of this use-after-free flaw could lead to kernel crashes (denial of service) or potentially enable privilege escalation or arbitrary code execution within the kernel context if an attacker can manipulate interrupt descriptors. This could compromise system availability and integrity, impacting critical services and infrastructure. Given Linux's prevalence in European data centers, telecommunications, and government systems, exploitation could disrupt operations, lead to data breaches, or facilitate lateral movement within networks. Although no active exploits are known, the vulnerability's presence in the kernel's interrupt handling—a core subsystem—makes it a high-value target for attackers aiming to gain kernel-level control. The impact is heightened in environments with multi-core processors where concurrent access to interrupt descriptors is common, increasing the likelihood of triggering the race condition.

European organizations should prioritize updating their Linux kernel to the patched versions that include the fix for CVE-2024-38385. Since the vulnerability stems from improper locking in kernel code, applying official kernel patches or upgrading to a kernel release that incorporates this fix is the most effective mitigation. For organizations using custom or long-term support kernels, backporting the patch may be necessary. Additionally, organizations should audit their systems to identify vulnerable kernel versions using package management tools or kernel version checks. Employing kernel hardening features such as KASAN during testing phases can help detect similar issues proactively. In environments where immediate patching is not feasible, minimizing exposure by restricting untrusted user access and monitoring for unusual kernel crashes or system instability related to interrupt handling is advisable. Finally, maintaining robust incident detection and response capabilities to quickly identify exploitation attempts is critical.