CVE-2023-52831: linux kernel — Fix

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 Unable to handle kernel paging request at virtual address fffe80027ab37080 partition_sched_domains_locked+0x318/0x880 rebuild_sched_domains_locked+0x37c/0x798 Aside of the resulting crash, it does not make any sense to offline the last last housekeeping CPU. Prevent this by masking out the non-housekeeping CPUs when selecting a target CPU for initiating the CPU unplug operation via the work queue.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-617 CWE-617

Affected Products

Vendor	Product	Versions
linux	linux_kernel	< 6.1.64
linux	linux_kernel	6.2 — 6.5.13
linux	linux_kernel	6.6 — 6.6.3

References

Advisories & Patches

https://git.kernel.org/stable/c/3073f6df783d9d75f7f69f73e16c7ef85d6cfb63 https://git.kernel.org/stable/c/335a47ed71e332c82339d1aec0c7f6caccfcda13 https://git.kernel.org/stable/c/3410b702354702b500bde10e3cc1f9db8731d908 https://git.kernel.org/stable/c/38685e2a0476127db766f81b1c06019ddc4c9ffa https://git.kernel.org/stable/c/3073f6df783d9d75f7f69f73e16c7ef85d6cfb63 https://git.kernel.org/stable/c/335a47ed71e332c82339d1aec0c7f6caccfcda13 https://git.kernel.org/stable/c/3410b702354702b500bde10e3cc1f9db8731d908 https://git.kernel.org/stable/c/38685e2a0476127db766f81b1c06019ddc4c9ffa

Frequently Asked Questions

What is CVE-2023-52831? +

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 Unable to handle kernel paging request at virtual address fffe80027ab37080 partition_sched_domains_locked+0x318/0x880 rebuild_sched_domains_locked+0x37c/0x798 Aside of the resulting crash, it does not make any sense to offline the last last housekeeping CPU. Prevent this by masking out the non-housekeeping CPUs when selecting a target CPU for initiating the CPU unplug operation via the work queue. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2023-52831? +

CVE-2023-52831 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2023-52831? +

CVE-2023-52831 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2023-52831? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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