CVE-2024-56535 is a vulnerability identified in the Linux kernel specifically within the WiFi driver component 'rtw89', which handles Realtek 89xx series wireless chipsets. The vulnerability arises in the function btc_fw_set_monreg(), where a call to kmalloc (kernel memory allocation function) may fail and return a NULL pointer. The original code did not check for this NULL return value, leading to a potential NULL pointer dereference when the pointer is subsequently used. This can cause a kernel crash (denial of service) or potentially lead to undefined behavior. The issue is a classic example of insufficient error handling for memory allocation failures in kernel code. The patch involves adding a check for the NULL return from kmalloc before proceeding, thereby preventing the NULL pointer dereference. The vulnerability affects specific Linux kernel versions identified by commit hashes (b952cb0a6e2d2e6942de3f8c6a1bd985815b9550). There are no known exploits in the wild as of the publication date (December 27, 2024), and no CVSS score has been assigned yet. The vulnerability is categorized as a stability and reliability issue that could be triggered by malformed or malicious WiFi frames or driver interactions, potentially leading to system crashes or kernel panics. Since it occurs in a kernel driver, exploitation would require local or privileged access or crafted wireless frames depending on the attack vector, but the exact exploitation complexity is not detailed.

For European organizations, the impact of CVE-2024-56535 primarily involves system availability and reliability. Systems running affected Linux kernel versions with the rtw89 WiFi driver enabled could experience kernel crashes or reboots due to NULL pointer dereferences triggered by this vulnerability. This could disrupt critical services, especially in environments relying on Linux-based infrastructure with Realtek 89xx wireless chipsets, such as enterprise laptops, embedded devices, or network appliances. Although no remote code execution or privilege escalation is indicated, denial of service conditions can impact operational continuity. Organizations in sectors like finance, healthcare, manufacturing, and government that use Linux systems with affected WiFi hardware may face interruptions or require emergency patching. The vulnerability does not appear to compromise confidentiality or integrity directly but can degrade system availability, which is critical for business operations and compliance with European data protection and operational resilience regulations.

1. Immediate application of the official Linux kernel patch that adds NULL pointer checks in btc_fw_set_monreg() to prevent the vulnerability. 2. For organizations unable to patch immediately, disable or blacklist the rtw89 WiFi driver if feasible, especially on critical systems, to mitigate exposure. 3. Monitor kernel logs and system stability for signs of crashes or panics related to WiFi driver activity. 4. Implement strict access controls to limit local user privileges, reducing the risk of exploitation via local attack vectors. 5. For wireless networks, employ network segmentation and monitoring to detect anomalous WiFi frames or driver interactions that could trigger the vulnerability. 6. Maintain up-to-date inventory of Linux kernel versions and hardware drivers to quickly identify affected systems. 7. Coordinate with hardware vendors and Linux distribution maintainers for timely updates and advisories. 8. Test patches in staging environments before deployment to ensure compatibility and stability.