Mitigation Strategies

The vulnerability is fixed by adding calls to of_node_put() to release the reference after extracting the needed arguments and on the error path when devm_kzalloc() fails.

To mitigate this vulnerability, you should update your Linux kernel to a version that includes this fix.

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Detection Guidance

This vulnerability is a refcount leak in the Linux kernel's pinctrl subsystem related to the function pcs_add_gpio_func(). It is caused by not releasing device_node references properly during iteration.

Detection of this specific refcount leak on a running system or network is not straightforward because it involves internal kernel memory management and reference counting.

There are no specific commands provided to detect this vulnerability directly.

However, general approaches to detect kernel refcount leaks include monitoring kernel logs for warnings or errors, using kernel debugging tools, or running static analysis tools on the kernel source code.

To confirm if your system is vulnerable, check the Linux kernel version and verify if it includes the patch that adds of_node_put() calls in pcs_add_gpio_func().

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Executive Summary

This vulnerability is a reference count leak in the Linux kernel's pinctrl subsystem, specifically in the function pcs_add_gpio_func().

The function of_parse_phandle_with_args() returns a device_node pointer with its reference count incremented. However, in a loop that iterates through all phandles, the code never releases these references, causing a reference count leak on each iteration.

The fix involves adding calls to of_node_put() to release the references after extracting the needed arguments and also on the error path when memory allocation fails.

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Impact Analysis

A reference count leak can lead to resource leaks in the kernel, potentially causing increased memory usage over time.

While this specific vulnerability does not have an assigned CVSS score or detailed impact description, such leaks can degrade system stability or performance if the leaked resources accumulate.

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