CVE-2025-40130

In the Linux kernel, the following vulnerability has been resolved:

scsi: ufs: core: Fix data race in CPU latency PM QoS request handling

The cpu_latency_qos_add/remove/update_request interfaces lack internal

synchronization by design, requiring the caller to ensure thread safety.

The current implementation relies on the 'pm_qos_enabled' flag, which is

insufficient to prevent concurrent access and cannot serve as a proper

synchronization mechanism. This has led to data races and list

corruption issues.

A typical race condition call trace is:

[Thread A]

ufshcd_pm_qos_exit()

--> cpu_latency_qos_remove_request()

--> cpu_latency_qos_apply();

--> pm_qos_update_target()

--> plist_del <--(1) delete plist node

--> memset(req, 0, sizeof(*req));

--> hba->pm_qos_enabled = false;

[Thread B]

ufshcd_devfreq_target

--> ufshcd_devfreq_scale

--> ufshcd_scale_clks

--> ufshcd_pm_qos_update <--(2) pm_qos_enabled is true

--> cpu_latency_qos_update_request

--> pm_qos_update_target

--> plist_del <--(3) plist node use-after-free

Introduces a dedicated mutex to serialize PM QoS operations, preventing

data races and ensuring safe access to PM QoS resources, including sysfs

interface reads.