CVE-2024-35932 is a vulnerability identified in the Linux kernel's Direct Rendering Manager (DRM) subsystem, specifically within the vc4 driver used for Broadcom VideoCore IV GPUs, commonly found in Raspberry Pi devices. The flaw arises from improper reference count management related to framebuffer (fb) objects during non-blocking atomic commits. The vulnerability manifests as a refcount underflow and use-after-free condition, triggered when the kernel incorrectly handles the lifecycle of framebuffer objects associated with DRM planes. The root cause is the direct access to the drm_plane's .state pointer instead of using the recommended drm_atomic_get_new_plane_state() helper function, leading to inconsistent reference counting between prepare_fb and cleanup_fb functions. This inconsistency can cause the reference count to be decremented more times than it was incremented or vice versa, resulting in memory corruption and potential kernel crashes. The kernel warning logs indicate a refcount_t underflow and a use-after-free error, which can destabilize the system or potentially be leveraged for privilege escalation or arbitrary code execution in a local context. The vulnerability affects Linux kernel versions including commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and likely other versions incorporating the flawed vc4 driver code. Although no known exploits are currently in the wild, the issue is significant due to the kernel-level memory corruption it causes. The vulnerability is particularly relevant for systems running Linux on Raspberry Pi hardware or other devices using the vc4 DRM driver. The fix involves correcting the reference counting logic and ensuring the use of drm_atomic_get_new_plane_state() to maintain state consistency during atomic commits.

For European organizations, the impact of CVE-2024-35932 depends largely on the deployment of Linux systems running the affected kernel versions with the vc4 DRM driver, notably Raspberry Pi devices. These devices are widely used in educational, industrial IoT, and prototyping environments across Europe. Exploitation could lead to kernel crashes causing denial of service, system instability, or potentially privilege escalation if combined with other vulnerabilities. This can disrupt critical services, especially in sectors relying on embedded Linux systems such as manufacturing automation, smart city infrastructure, and research institutions. While the vulnerability requires local access and is not remotely exploitable by itself, compromised or untrusted users could leverage it to escalate privileges or cause system failures. The use-after-free condition could also be a stepping stone for more sophisticated attacks if chained with other exploits. Given the increasing adoption of Raspberry Pi and similar hardware in European educational and industrial contexts, the vulnerability poses a moderate risk to availability and integrity of affected systems.

European organizations should prioritize patching Linux kernels on all affected devices, especially Raspberry Pi systems running the vc4 DRM driver. This includes updating to the latest stable kernel versions where the fix for CVE-2024-35932 has been applied. For environments where immediate patching is not feasible, organizations should restrict local access to trusted users only and monitor for unusual kernel warnings or crashes related to DRM operations. Implementing strict user privilege separation and employing kernel hardening techniques such as SELinux or AppArmor can reduce the risk of exploitation. Additionally, organizations should audit their use of embedded Linux devices and ensure that firmware and software are regularly updated. For developers and system integrators, avoiding direct access to drm_plane->state and using drm_atomic_get_new_plane_state() as recommended will prevent similar issues in custom kernel modules or drivers. Finally, maintaining comprehensive logging and alerting on kernel errors can facilitate early detection of exploitation attempts.