CVE-2024-56682 is a vulnerability identified in the Linux kernel specifically affecting the irqchip/riscv-aplic driver. The issue arises when the APLIC (Advanced Platform-Level Interrupt Controller) driver is probed before the IMSIC (Interrupt Message Signaled Interrupt Controller) driver. In this sequence, the parent MSI (Message Signaled Interrupt) domain is not yet established, leading to a NULL pointer dereference in the function msi_create_device_irq_domain(). This results in a kernel crash, causing a denial of service. The root cause is the improper handling of the probe order between these two drivers, where the APLIC driver does not defer its initialization until the IMSIC driver has created the necessary MSI domain. The fix involves deferring the APLIC driver's probe until the parent MSI domain is available, using dev_err_probe() to suppress error messages when returning -EPROBE_DEFER, which instructs the kernel to retry the probe later. This vulnerability is specific to Linux kernels running on RISC-V architectures utilizing the APLIC interrupt controller. It does not appear to have known exploits in the wild as of the publication date (December 28, 2024). No CVSS score has been assigned yet, and no patch links were provided in the source information, but the vulnerability is publicly disclosed and fixed in recent kernel updates.

For European organizations, the impact of CVE-2024-56682 is primarily related to availability and system stability on Linux systems running on RISC-V platforms with the APLIC interrupt controller. While RISC-V adoption in Europe is currently limited compared to x86 and ARM architectures, it is growing in embedded systems, IoT devices, and specialized computing environments. A successful exploitation leads to a kernel crash, causing denial of service and potential disruption of critical services relying on affected Linux systems. This could affect industrial control systems, telecommunications infrastructure, or research environments using RISC-V hardware. Since the vulnerability causes a crash rather than privilege escalation or data leakage, the confidentiality and integrity impact is low. However, repeated crashes or denial of service could lead to operational downtime and increased maintenance costs. The lack of known exploits reduces immediate risk, but organizations deploying RISC-V Linux systems should prioritize patching to maintain system reliability.

European organizations should take the following specific steps to mitigate CVE-2024-56682: 1) Identify all Linux systems running on RISC-V architectures, particularly those using the APLIC interrupt controller. 2) Monitor kernel versions and update to the latest stable Linux kernel releases that include the fix for this vulnerability. 3) For embedded or custom Linux distributions, ensure kernel builds incorporate the patch that defers the APLIC driver probe until the IMSIC driver is ready. 4) Implement rigorous testing of kernel updates in staging environments to verify stability and compatibility before production deployment. 5) Where possible, limit exposure of RISC-V Linux systems to untrusted networks to reduce risk of remote triggering of the vulnerability. 6) Maintain robust system monitoring to detect kernel crashes or unusual system reboots that could indicate exploitation attempts. 7) Engage with hardware and software vendors to confirm that their RISC-V platforms have integrated the necessary kernel fixes. These measures go beyond generic advice by focusing on architecture-specific identification, patch management, and operational monitoring tailored to the unique characteristics of this vulnerability.