CVE-2024-35927 is a medium-severity vulnerability in the Linux kernel related to the Direct Rendering Manager (DRM) subsystem, specifically within the drm_kms_helper component that manages kernel mode setting and output polling. The vulnerability arises because drm_kms_helper_poll_disable() does not verify whether output polling support has been initialized before attempting to disable it. This omission can lead to a suspend failure in drivers that do not initialize connector polling, such as the hyperv-drm driver used in Microsoft Hyper-V virtualized environments. When the system attempts to suspend without this check, it triggers a kernel warning and a stack trace indicating a failure in the workqueue flushing mechanism (__flush_work.isra.0). The root cause is that suspend and resume helper functions (drm_mode_config_helper_suspend() and drm_mode_config_helper_resume()) are invoked without confirming polling initialization, leading to improper handling of the polling state and ultimately causing system instability during suspend operations. The issue is particularly relevant for virtual machines running on Hyper-V with the hyperv-drm driver. The vulnerability has been addressed by adding checks to ensure polling is initialized before disabling it and by avoiding calls to suspend/resume helpers if polling is not set up. The CVSS v3.1 score is 5.5 (medium), reflecting a local attack vector requiring low privileges, no user interaction, and resulting in availability impact without confidentiality or integrity compromise. No known exploits are reported in the wild as of the publication date. The vulnerability affects Linux kernel versions identified by the commit hashes provided, and the fix is integrated into kernel updates post-disclosure.

For European organizations, the impact of CVE-2024-35927 primarily concerns systems running Linux kernels with the affected drm_kms_helper code, especially those deployed in virtualized environments using Microsoft Hyper-V. The vulnerability can cause system suspend operations to fail, potentially leading to system instability, unexpected reboots, or denial of service conditions during power management events. This can disrupt critical services, especially in data centers or cloud environments where virtual machines rely on suspend/resume cycles for maintenance or power saving. Although the vulnerability does not compromise confidentiality or integrity, availability degradation can affect operational continuity. Organizations using Linux-based virtual machines on Hyper-V hosts, common in enterprise and cloud infrastructures across Europe, may experience increased downtime or require manual intervention to recover from suspend failures. The issue is less likely to affect bare-metal Linux servers or those using other virtualization platforms. Given the medium severity and local attack vector, exploitation would generally require access to the affected system with low privileges, limiting remote exploitation risks but emphasizing the need for internal security controls and patch management.

To mitigate CVE-2024-35927, European organizations should: 1) Apply the latest Linux kernel updates that include the patch fixing the polling initialization checks in drm_kms_helper. This is the most effective mitigation. 2) For virtualized environments using Hyper-V, ensure that the hyperv-drm driver and related kernel modules are updated to versions containing the fix. 3) Implement strict access controls and monitoring on systems running affected kernels to prevent unauthorized local access, as exploitation requires local privileges. 4) Test suspend/resume operations in controlled environments after patching to verify stability and detect any residual issues. 5) Consider disabling connector polling or modifying power management configurations temporarily if immediate patching is not feasible, though this may impact functionality. 6) Maintain robust backup and recovery procedures to minimize downtime in case of suspend failures. 7) Monitor vendor advisories and Linux kernel mailing lists for any emerging exploit information or additional patches. These steps go beyond generic advice by focusing on virtualization-specific configurations and local privilege considerations.