CVE-2024-44931 is a vulnerability identified in the Linux kernel's GPIO subsystem, specifically within the gpio_device_get_desc() function. The issue arises because the function uses an offset value provided by userspace without proper sanitization when indexing into the gpio descriptor array. This lack of bounds checking allows userspace applications to trigger speculative execution paths that read memory outside the intended gpio descriptor array. Speculative execution is a performance optimization in modern CPUs where the processor guesses the path of execution and executes instructions ahead of time. However, this can lead to speculative information leaks, where sensitive data from adjacent memory locations may be exposed transiently during speculation, potentially allowing attackers to infer privileged information through side-channel attacks. The vulnerability is exploited by invoking gpio_ioctl() with an out-of-range offset, which is then used unsafely as an array index. The Linux kernel patch mitigates this by applying array_index_nospec(), a kernel helper function designed to sanitize array indices and prevent speculative out-of-bounds reads. This fix effectively blocks the speculative leak vector by ensuring that any out-of-range index is clamped before use. The vulnerability was discovered through static analysis using Coverity SAST by Synopsys, indicating it was found proactively rather than through active exploitation. No known exploits are reported in the wild as of the publication date. The affected versions are specific Linux kernel commits prior to the patch, and the vulnerability was publicly disclosed on August 26, 2024. No CVSS score has been assigned yet.

For European organizations, this vulnerability poses a risk primarily to systems running Linux kernels with the affected GPIO code, which is common in embedded devices, IoT infrastructure, industrial control systems, and servers that interact with hardware peripherals via GPIO interfaces. The speculative leak could potentially expose sensitive kernel memory contents, which might include cryptographic keys, credentials, or other confidential information. While exploitation requires local userspace access, this could be leveraged by malicious insiders, compromised containers, or untrusted applications to escalate privileges or extract sensitive data. The impact on confidentiality is moderate to high depending on the data exposed, while integrity and availability impacts are minimal as the vulnerability does not directly allow code execution or denial of service. Given the widespread use of Linux in European critical infrastructure, telecommunications, and manufacturing sectors, the vulnerability could be leveraged to undermine system security and data privacy. However, the lack of known exploits and the requirement for local access reduce the immediate threat level. Organizations relying on embedded Linux devices or custom hardware running vulnerable kernels should be particularly vigilant.

European organizations should prioritize updating Linux kernels to the patched versions that include the array_index_nospec() fix for gpio_device_get_desc(). For embedded and IoT devices where kernel updates may be slower, organizations should implement strict access controls to limit userspace access to GPIO interfaces, including restricting ioctl calls to trusted processes only. Employing mandatory access control frameworks such as SELinux or AppArmor can help enforce these restrictions. Additionally, monitoring for unusual ioctl usage patterns or attempts to access out-of-range GPIO offsets can provide early detection of exploitation attempts. Organizations should also audit container and virtualization environments to ensure that untrusted containers or virtual machines cannot access GPIO interfaces directly. For critical systems, consider hardware-level protections or isolating devices with sensitive GPIO interactions from general-purpose user environments. Finally, maintain an inventory of Linux kernel versions in use across all devices to identify and remediate vulnerable instances promptly.