CVE-2024-41932

What it actually does

The flaw triggers a spurious kernel WARN when sched_setaffinity races with a cpuset update such that the requested task affinity has zero overlap with the cpuset mask; the code already falls back to the cpuset mask but still fires the warning.

Why it matters to the business

Produces noisy kernel warnings in environments that use cpusets and dynamic per-task affinity (e.g., containers or orchestration platforms), increasing log volume and alert fatigue with no loss of functionality or data exposure. Low EPSS and no KEV listing indicate minimal operational urgency.

How an attack unfolds

An attacker with the ability to both modify cpuset CPU masks and call sched_setaffinity concurrently can deliberately trigger the race, but the only observable effect is a kernel warning; the condition is trivial to create and carries no privilege escalation or denial-of-service impact beyond log spam.

How to fix it

Upgrade the Linux kernel to a version containing commit 5c3fb75f538cfcb886f6dfeb497d99fc2f263ee6 or apply the equivalent stable backport; for affected Ubuntu Pro 16.04 systems install package version 2.4.5-1ubuntu0.1~esm1 or later.

How to confirm the fix worked

Verify the running kernel contains commit 5c3fb75f or is at the fixed package version; reproduce the original test case (cpuset mask changes concurrent with sched_setaffinity) and confirm no WARN is emitted.

Typical attack path

1. Place a target process inside a cpuset cgroup
2. Repeatedly shrink/expand the cpuset CPU mask from another thread
3. Concurrently invoke sched_setaffinity (via taskset or syscall) requesting an affinity outside the current cpuset mask
4. Observe the WARN in dmesg or kernel logs

How to detect it

Search kernel logs (dmesg, journalctl, /var/log/kern.log) for WARN messages emitted from sched_setaffinity around cpuset mask updates; correlate with processes performing frequent affinity changes inside cpuset cgroups.

What your security team should do

• Prioritize kernel upgrades on systems that heavily use cpusets or container runtimes
• Add the fixed commit ID to internal patch-management tracking
• Suppress or rate-limit the specific sched_setaffinity WARN until patches are deployed if log volume is problematic