CVE-2026-98529 in Linux
Summary
by MITRE • 10/18/2026
In the Linux kernel, the following vulnerability has been resolved:
gpio: arizona: Fix runtime PM leak in arizona_gpio_direction_out()
Switching a persistent GPIO line from input to output acquires a runtime PM reference on the parent device, but if the subsequent regmap_update_bits() fails the reference is never dropped and no later direction_in() can balance it since the direction was never changed. Drop the reference on the update failure path.
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Analysis
by VulDB Data Team • 10/18/2026
The Linux kernel GPIO subsystem for Arizona audio codecs contains a resource management flaw within the arizona_gpio_direction_out function that results in a runtime power management leak. This vulnerability arises from an asymmetry in how system resources are acquired and released during state transitions of General Purpose Input/Output lines. Specifically, when a persistent GPIO line is switched from an input configuration to an output configuration, the driver correctly acquires a runtime Power Management reference on the parent device to ensure it remains active while the hardware register is being modified. This acquisition is necessary because changing pin direction often requires accessing specific registers that may be powered down if the system enters a low-power state. However, the implementation fails to handle error conditions gracefully during this critical window.
The technical flaw occurs when the subsequent call to regmap_update_bits() encounters an error and returns a failure code. In such scenarios, the function exits without releasing the previously acquired runtime PM reference. This creates a situation where the parent device is kept in an active power state indefinitely because the reference count is never decremented. The severity of this issue is compounded by the fact that subsequent attempts to change the GPIO direction back to input via arizona_gpio_direction_in() cannot balance or release this leaked reference. Since the initial direction change operation failed, the internal state machine does not recognize a valid transition from output to input for the purpose of resource cleanup, leaving the orphaned reference attached to the device structure permanently until system reboot or module unload.
From an operational perspective, this runtime PM leak leads to increased power consumption and potential thermal issues in embedded systems utilizing Arizona codecs. Devices that rely on aggressive power saving strategies may find themselves unable to enter deep sleep states because the GPIO subsystem holds a wake lock through the leaked reference. Over time, as more GPIO lines are configured or reconfigured with failing register writes, multiple such leaks can accumulate, potentially exhausting available runtime PM references and causing broader system instability or preventing other drivers from managing power correctly. This aligns with CWE-401, which describes missing release of a resource after successful acquisition, leading to resource exhaustion.
The vulnerability is further contextualized by ATT&CK technique T1529, System Shutdown/Reboot, as the only reliable way to clear these leaked references in many embedded environments without restarting the entire system is often difficult or impossible for running services. To mitigate this issue, developers must ensure that all error paths in power management critical functions explicitly release acquired resources before returning failure codes. The fix involves adding a call to put the runtime PM reference on the parent device immediately after detecting a regmap_update_bits() failure within arizona_gpio_direction_out(). This ensures that even if hardware communication fails, the system state remains consistent and no artificial wake locks are left behind. System administrators should monitor power states in affected systems and apply kernel patches promptly to restore proper power management behavior.