CVE-2026-90147 in Linux
Summary
by MITRE • 09/17/2026
In the Linux kernel, the following vulnerability has been resolved:
clk: devres: fix cleanup in devm_clk_get_optional_enabled_with_rate()
devm_clk_get_optional_enabled_with_rate() registers its cleanup action before setting the clock rate. If setting the rate fails, it attempts to disable and unprepare a clock that was never enabled. This issue was spotted while reviewing "rust: clk: add devres-managed clks" [1].
Register the cleanup action only after successfully preparing and enabling the clock.
[1]: https://lore.kernel.org/rust-for-linux/[email protected]
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Analysis
by VulDB Data Team • 09/17/2026
The Linux kernel's device resource management subsystem provides a mechanism for automatically cleaning up allocated resources when a driver is unloaded or an error occurs during initialization. A specific vulnerability was identified in the function devm_clk_get_optional_enabled_with_rate, which manages clock resources by preparing and enabling them while registering a cleanup action to reverse these operations if necessary. The core technical flaw lies in the ordering of operations within this function. Specifically, the code registers the cleanup handler before verifying that the clock rate has been successfully set. This sequencing error creates a race condition-like state where, if setting the clock rate fails due to hardware constraints or invalid parameters, the registered cleanup action will still execute upon subsequent errors or driver unloading.
When the failure occurs after registration but before successful enablement, the cleanup routine attempts to disable and unprepare a clock that was never actually enabled or prepared in the first place. This results in an improper state transition within the kernel's clock framework. Such operations on uninitialized or inactive hardware resources can lead to undefined behavior, including potential kernel panics, memory corruption, or instability in power management subsystems. The issue highlights a critical oversight in defensive programming practices where error handling paths must account for partial initialization states rather than assuming full resource acquisition before registering teardown logic.
From a security and stability perspective, this vulnerability falls under CWE-672, which pertains to the use of operations after failure checks are not properly handled or ordered correctly. It also relates to CWE-390 regarding detection of error conditions without proper action, as the system fails to align its cleanup mechanisms with actual resource states. In terms of MITRE ATT&CK mapping, while this is primarily a stability issue rather than an exploit vector for malicious actors, it represents a weakness in software quality assurance that could potentially be leveraged in denial-of-service scenarios if triggered repeatedly or under specific timing conditions by local users with appropriate privileges to load drivers or manipulate clock configurations.
The operational impact of this flaw includes potential system crashes during driver initialization sequences where clock rate setting is optional but attempted, leading to reduced reliability for embedded systems and devices relying on precise power management. To mitigate this vulnerability, the fix involves reordering the code logic so that the cleanup action is registered only after both preparing and enabling the clock have been successfully completed. This ensures that the teardown routine will never attempt to reverse operations that were not performed. Developers should audit similar devres functions for analogous ordering issues where resource acquisition steps are interleaved with registration of automatic cleanup handlers, ensuring that all prerequisites for successful operation are met before binding the failure path to those resources.