CVE-2026-74463

/// Technical description

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

i2c: jz4780: Cache host clock rate at probe to prevent CCF prepare_lock deadlock

Fix a severe AB/BA deadlock between the Common Clock Framework (CCF)

and the I2C adapter lock, which triggers when an I2C-controlled clock

generator client (like the Si5351) is registered or modified under the CCF.

During an i2c client clock (generator) frequency change, the CCF acquires its global

'prepare_lock' mutex and the driver calls i2c_transfer() to update the client's

chip registers, stalling for the adapter's I2C bus lock.

Concurrently, an independent, parallel transfer on the same bus (e.g., a GPIO

expander handling LEDs) can hold the I2C adapter lock. Inside this parallel

transfer path, jz4780_i2c_set_speed() calls clk_get_rate() on the host

controller's input clock to calculate bus timings. This call attempts to acquire

the blocked CCF 'prepare_lock', creating a circular dependency that freezes

the system.

The jz4780 host

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References