The Linux kernel blk-cgroup subsystem had a disk reference leak vulnerability in the blkcg_maybe_throttle_current() function. When certain lookups (blkcg, blkg, or blkg_tryget) fail, the function jumps to an error label that only calls rcu_read_unlock() without releasing the disk reference acquired by blkcg_schedule_throttle() via get_device(). Since current->throttle_disk is set to NULL before the lookup, blkcg_exit() cannot release the reference either, causing the disk reference to leak indefinitely. The fix restores the missing reference release that was dropped during the conversion from request_queue to gendisk.

The vulnerability causes a disk reference leak in the Linux kernel's blk-cgroup subsystem, which can lead to resource exhaustion or system instability over time due to unreleased disk references. There is no indication of direct privilege escalation or remote exploitation. The CVSS vector indicates local attack with low privileges and partial impact on availability.

A fix is available in Linux kernel versions 7.0.0-28.28.1 and later. Users should update to these or newer kernel versions to remediate the issue. Since this is not a cloud service, manual patching is required. There are no vendor advisories stating no action is required, so applying the official fix is recommended.