Linux Kernel Global State Lock Contention Vulnerability in DRM/MSM/MDP5

A vulnerability in the Linux kernel's DRM/MSM/MDP5 component has been addressed. The issue involved improper handling of global state locks, which could lead to contention without the appropriate backoff, potentially causing performance issues. This vulnerability was flagged by the new CONFIG_DRM_DEBUG_MODESET_LOCK during continuous integration testing, indicating a problem with how locks were managed, particularly in relation to pipeline releases and plane atomic checks.

Impact

The vulnerability could cause performance degradation by allowing lock contention to occur without proper backoff, disrupting normal operations in the affected component.

Reproduction

The vulnerability can be reproduced by enabling the CONFIG_DRM_DEBUG_MODESET_LOCK option in the Linux kernel. This will trigger a warning about the DRM modeset lock handling, particularly during operations that involve releasing pipes and checking plane states in the MDP5 component. The warning indicates that the lock was contended, but the global state was not properly managed, creating a potential issue that the vulnerability addresses.

Remediation

Users can apply the latest patches available in the Linux kernel repository to address this vulnerability. These patches can be found in the official Linux kernel Git repository, under the 'stable' branch.