CVE-2022-49726: clocksource: hyper-v: unexport __init-annotated hv_init_clocksource()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-02-26 · updated 2026-06-17
Weakness: CWE-908

Description

In the Linux kernel, the following vulnerability has been resolved: clocksource: hyper-v: unexport __init-annotated hv_init_clocksource() EXPORT_SYMBOL and __init is a bad combination because the .init.text section is freed up after the initialization. Hence, modules cannot use symbols annotated __init. The access to a freed symbol may end up with kernel panic. modpost used to detect it, but it has been broken for a decade. Recently, I fixed modpost so it started to warn it again, then this showed up in linux-next builds. There are two ways to fix it: - Remove __init - Remove EXPORT_SYMBOL I chose the latter for this case because the only in-tree call-site, arch/x86/kernel/cpu/mshyperv.c is never compiled as modular. (CONFIG_HYPERVISOR_GUEST is boolean)

Affected products

Linux kernel: from 5.3 before 5.4.200; from 5.5 before 5.10.124; from 5.11 before 5.15.49; from 5.16 before 5.18.6; 5.19-rc1, 5.19-rc2 — fixed in 5.10.124, 5.15.49, 5.18.6, 5.4.200

How to fix

Upgrade to a fixed version: Linux kernel 5.10.124, 5.15.49, 5.18.6, 5.4.200. Check the vendor advisory for mitigations.

References

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