CVE-2025-68214

/// Technical description

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

timers: Fix NULL function pointer race in timer_shutdown_sync()

There is a race condition between timer_shutdown_sync() and timer

expiration that can lead to hitting a WARN_ON in expire_timers().

The issue occurs when timer_shutdown_sync() clears the timer function

to NULL while the timer is still running on another CPU. The race

scenario looks like this:

CPU0 CPU1

<SOFTIRQ>

lock_timer_base()

expire_timers()

base->running_timer = timer;

unlock_timer_base()

[call_timer_fn enter]

mod_timer()

...

timer_shutdown_sync()

lock_timer_base()

// For now, will not detach the timer but only clear its function to NULL

if (base->running_timer != timer)

ret = detach_if_pending(timer, base, true);

if (shutdown)

timer->function = NULL;

unlock_timer_base()

[call_timer_fn exit]

lock_timer_base()

base->running_timer = NULL;

unlock_timer_base()

...

// Now timer

/// 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