CVE-2026-97905

Summary

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

cpufreq: zero-initialize policy cpumask before sysfs publication

cpufreq_policy_alloc() allocates policy->cpus with alloc_cpumask_var(), i.e. without __GFP_ZERO, unlike the sibling related_cpus and real_cpus masks. With CONFIG_CPUMASK_OFFSTACK=y the mask is a separate kmalloc_node() allocation, so its bitmap holds whatever the slab allocator left behind:

cpufreq_online() cpufreq_policy_alloc() alloc_cpumask_var(&policy->cpus) /* bitmap is uninitialized / kobject_init_and_add() / policy%u/ appears in sysfs / cpufreq_policy_online() cpumask_copy(policy->cpus, cpumask_of(cpu)) / first valid value */

This leaves a window in which the sysfs attributes are already reachable while policy->cpus is still garbage. show()/store() gate on policy_is_inactive(), i.e. cpumask_empty(policy->cpus), so a non-zero bitmap makes them run the attribute callbacks on a policy that is not initialized yet.

Fix this by using zalloc_cpumask_var() for policy->cpus.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/0de2f3918fbbbb767e7e716178194b66560dd12a
• https://git.kernel.org/stable/c/6e166b9281dec98aed19213a84235250e5fdb081
• https://git.kernel.org/stable/c/bbc0472d2270bf732142ca71579d6ede636174ed
• https://git.kernel.org/stable/c/54d37bcf2f497140b9207968557ddb484058e749

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