CVE-2023-52831

/// Technical description

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

cpu/hotplug: Don't offline the last non-isolated CPU

If a system has isolated CPUs via the "isolcpus=" command line parameter,

then an attempt to offline the last housekeeping CPU will result in a

WARN_ON() when rebuilding the scheduler domains and a subsequent panic due

to and unhandled empty CPU mas in partition_sched_domains_locked().

cpuset_hotplug_workfn()

rebuild_sched_domains_locked()

ndoms = generate_sched_domains(&doms, &attr);

cpumask_and(doms[0], top_cpuset.effective_cpus, housekeeping_cpumask(HK_FLAG_DOMAIN));

Thus results in an empty CPU mask which triggers the warning and then the

subsequent crash:

WARNING: CPU: 4 PID: 80 at kernel/sched/topology.c:2366 build_sched_domains+0x120c/0x1408

Call trace:

build_sched_domains+0x120c/0x1408

partition_sched_domains_locked+0x234/0x880

rebuild_sched_domains_locked+0x37c/0x798

rebuild_sched_domains+0x30/0x58

cpuset_hotplug_workfn+0x2a8/0x930

Una

/// 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