CVE-2022-48961: net: mdio: fix unbalanced fwnode reference count in mdio_device_release()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-10-21 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: net: mdio: fix unbalanced fwnode reference count in mdio_device_release() There is warning report about of_node refcount leak while probing mdio device: OF: ERROR: memory leak, expected refcount 1 instead of 2, of_node_get()/of_node_put() unbalanced - destroy cset entry: attach overlay node /spi/soc@0/mdio@710700c0/ethernet@4 In of_mdiobus_register_device(), we increase fwnode refcount by fwnode_handle_get() before associating the of_node with mdio device, but it has never been decreased in normal path. Since that, in mdio_device_release(), it needs to call fwnode_handle_put() in addition instead of calling kfree() directly. After above, just calling mdio_device_free() in the error handle path of of_mdiobus_register_device() is enough to keep the refcount balanced.

Affected products

Linux kernel: from 4.5 before 5.15.83; from 5.16 before 6.0.13; 6.1-rc1, 6.1-rc2, 6.1-rc3, 6.1-rc4, 6.1-rc5, 6.1-rc6 (+2) — fixed in 5.15.83, 6.0.13

How to fix

Upgrade to a fixed version: Linux kernel 5.15.83, 6.0.13. Check the vendor advisory for mitigations.

References

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