kho: fix size calculation in kho_preserved_memory_reserve() (CVE-2026-89568) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-89568

kho: fix size calculation in kho_preserved_memory_reserve()

Answer in brief

CVE-2026-89568 records a Unknown severity vulnerability in kho: fix size calculation in kho_preserved_memory_reserve(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 11, 2026Updated Sep 11, 2026Source checked Sep 11, 2026First seen by HOL Sep 11, 2026Material review Sep 11, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=fc33e4b44b2717feba2f6f07ce7943a96499c9ec <42a6f03cf352eb6e6dbeef95e75e686f4cdb9bd1 \|\| >=fc33e4b44b2717feba2f6f07ce7943a96499c9ec <3a0b8fa2eb36afc88b62a95f33f0c77c71fa5ded	42a6f03cf352eb6e6dbeef95e75e686f4cdb9bd1, 3a0b8fa2eb36afc88b62a95f33f0c77c71fa5ded
Linux/Linuxgeneric	6.16	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 42a6f03cf352eb6e6dbeef95e75e686f4cdb9bd1 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 11, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: kho: fix size calculation in kho_preserved_memory_reserve() kho_preserved_memory_reserve() calculates the size of a preservation by doing 1 << (order + PAGE_SHIFT). Since the '1' is a 32-bit integer, it can only be shifted by 31. That is, it will only work for preservations up to 2 GiB. Larger preservations will trigger undefined behaviour. While preservations larger than 2 GiB can't be obtained via folios currently, they can be obtained via kho_preserve_pages(). For example, memblock reserve_mem uses kho_preserve_pages(). Reservations larger than 2 GiB are valid and will trigger this bug if properly aligned. Fix it by using 1UL for shifting.

Quoted source text, attributed separately from HOL analysis.