CVE-2026-23100

/// Technical description

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

mm/hugetlb: fix hugetlb_pmd_shared()

Patch series "mm/hugetlb: fixes for PMD table sharing (incl. using

mmu_gather)", v3.

One functional fix, one performance regression fix, and two related

comment fixes.

I cleaned up my prototype I recently shared [1] for the performance fix,

deferring most of the cleanups I had in the prototype to a later point.

While doing that I identified the other things.

The goal of this patch set is to be backported to stable trees "fairly"

easily. At least patch #1 and #4.

Patch #1 fixes hugetlb_pmd_shared() not detecting any sharing

Patch #2 + #3 are simple comment fixes that patch #4 interacts with.

Patch #4 is a fix for the reported performance regression due to excessive

IPI broadcasts during fork()+exit().

The last patch is all about TLB flushes, IPIs and mmu_gather.

Read: complicated

There are plenty of cleanups in the future to be had + one reasonable

optimization on x86. But

/// 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