CVE-2022-49675

/// Technical description

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

tick/nohz: unexport __init-annotated tick_nohz_full_setup()

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 had been broken for a decade.

Commit 28438794aba4 ("modpost: fix section mismatch check for exported

init/exit sections") fixed it so modpost started to warn it again, then

this showed up:

MODPOST vmlinux.symvers

WARNING: modpost: vmlinux.o(___ksymtab_gpl+tick_nohz_full_setup+0x0): Section mismatch in reference from the variable __ksymtab_tick_nohz_full_setup to the function .init.text:tick_nohz_full_setup()

The symbol tick_nohz_full_setup is exported and annotated __init

Fix this by removing the __init annotation of tick_nohz_full_setup or drop the export.

Drop the export because tick_noh

/// 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