CVE-2026-23332

/// Technical description

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

cpufreq: intel_pstate: Fix crash during turbo disable

When the system is booted with kernel command line argument "nosmt" or

"maxcpus" to limit the number of CPUs, disabling turbo via:

echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo

results in a crash:

PF: supervisor read access in kernel mode

PF: error_code(0x0000) - not-present page

PGD 0 P4D 0

Oops: Oops: 0000 [#1] SMP PTI

...

RIP: 0010:store_no_turbo+0x100/0x1f0

...

This occurs because for_each_possible_cpu() returns CPUs even if they

are not online. For those CPUs, all_cpu_data[] will be NULL. Since

commit 973207ae3d7c ("cpufreq: intel_pstate: Rearrange max frequency

updates handling code"), all_cpu_data[] is dereferenced even for CPUs

which are not online, causing the NULL pointer dereference.

To fix that, pass CPU number to intel_pstate_update_max_freq() and use

all_cpu_data[] for those CPUs for which there is a valid cpufreq policy.

/// 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