CVE-2024-40965

What it actually does

The flaw allows a deadlock when clk_get_rate is called during an i2c transfer while the clk mutex is already held by a clock provider such as an audio codec driver, creating a circular wait between the i2c and clock subsystems.

Why it matters to the business

Linux systems using affected i2c-lpi2c drivers and certain audio codecs can experience hard hangs requiring manual intervention or reboot, disrupting services on servers, embedded devices, and desktops with widespread kernel adoption amplifying operational downtime.

How an attack unfolds

An attacker with the ability to trigger i2c activity combined with clock provider registration (for example by loading or configuring a tlv320aic32x4 codec) forces the race between mutex acquisition in clk_get_rate and the clock subsystem, resulting in deadlock; listed threat actors in espionage and financially motivated campaigns have targeted similar Linux kernel race conditions for denial-of-service or persistence.

How to fix it

Update the Linux kernel to the fixed commit d038693e08adf9c162c6377800495e4f5a2df045 or later stable releases that cache the clock rate under lock instead of calling clk_get_rate on every transfer.

How to confirm the fix worked

Verify the running kernel contains commit d038693e08adf9c162c6377800495e4f5a2df045 via git log or uname output against the affected stable trees; test by adding a tlv320aic32x4 codec and confirming no deadlock occurs during i2c transfers.

Typical attack path

1. Gain local execution or configuration rights on a Linux system using the vulnerable i2c-lpi2c driver
2. Trigger or wait for an i2c transfer while a clock provider registers its clock
3. Force the clk mutex to be held during the subsequent clk_get_rate call inside the transfer path
4. Induce the circular wait resulting in deadlock

How to detect it

Review kernel logs for deadlock warnings, hung task messages, or mutex contention involving clk_get_rate and i2c-lpi2c transfers; correlate with device addition events for audio codecs.

What your security team should do

• Apply the kernel fix containing commit d038693e08adf9c162c6377800495e4f5a2df045 immediately on all affected distributions
• Prioritize systems exposing i2c audio or sensor devices for patching within the CISA-style remediation window even though not listed in KEV
• Monitor for kernel deadlock reports involving clk and i2c subsystems until patches are deployed fleet-wide