CVE-2024-35836 is a vulnerability identified in the Linux kernel's dpll (Display Phase-Locked Loop) subsystem related to the handling of pin resources when kernel modules are rebound. Specifically, the issue arises when a kernel module is unbound but the pin resources it used are not fully freed because other kernel module instances referencing the same PCI device still hold references to those pins. Upon rebinding the kernel module, the pin properties are not updated correctly because these properties are only assigned when memory for the pin is initially allocated. Consequently, the pointer to the pin properties continues to reference memory that belonged to the previously unbound kernel module, which has since been deallocated. If a pin dump operation is invoked while the system is in this inconsistent state, it results in a kernel crash due to dereferencing invalid memory. The fix implemented involves storing persistent pin properties within the dpll subsystem itself, copying the pin property content from the kernel module at allocation time rather than relying on the kernel module's memory. This change ensures that pin properties remain valid and consistent even when kernel modules are rebound, preventing the crash scenario.

For European organizations, this vulnerability poses a risk primarily in environments running Linux kernels with affected versions, especially those utilizing PCI devices managed by the dpll subsystem. The kernel crash caused by this vulnerability can lead to system instability and denial of service (DoS) conditions, which may disrupt critical services, particularly in data centers, cloud infrastructure, and embedded systems relying on Linux. While this vulnerability does not appear to allow privilege escalation or arbitrary code execution, the resulting kernel panic can cause downtime and potential data loss if systems are not properly configured for resilience. Industries such as telecommunications, manufacturing, and financial services in Europe that depend heavily on Linux-based infrastructure could experience operational impacts. Additionally, the lack of known exploits in the wild reduces immediate risk but does not eliminate the potential for future exploitation attempts, especially in targeted attacks or sophisticated threat actor campaigns.

European organizations should prioritize updating their Linux kernel to the patched version that addresses CVE-2024-35836 as soon as it becomes available from their Linux distribution vendors. Since the vulnerability involves kernel module rebinding and pin resource management, system administrators should audit and monitor kernel module usage, particularly for PCI devices managed by the dpll subsystem. Implementing robust system monitoring to detect kernel crashes and unusual pin dump invocations can help identify exploitation attempts. For critical systems, consider deploying kernel live patching solutions where available to minimize downtime during patch application. Additionally, organizations should ensure that backup and recovery procedures are in place to mitigate the impact of potential system crashes. Network segmentation and limiting access to systems that perform pin dump operations can reduce the attack surface. Finally, maintain vigilance on security advisories from Linux kernel maintainers and relevant distribution vendors for updates and further guidance.