---
id: CVE-2026-98650
title: 'KVM: s390: Fix potential races in dat skey functions'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  KVM: s390: Fix potential races in dat skey functions

  When dat_cond_set_storage_key() finds a large page, it will
  conditionally set the storage key in absolute memory u…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 8e03e8316eb242af307d1c789d09f1a1457cf9a3 <
    c958f0498891203fddf2764b28f8b102c6bfd719
  - >-
    Linux >= 8e03e8316eb242af307d1c789d09f1a1457cf9a3 <
    27554b9505ddfc0aeab466aeb60929dfa17284c7
  - Linux 7.0
published: '2026-10-18'
updated: '2026-10-18'
sourceUpdated: '2026-10-18T15:20:22.173Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98650'
references:
  - url: 'https://git.kernel.org/stable/c/c958f0498891203fddf2764b28f8b102c6bfd719'
  - url: 'https://git.kernel.org/stable/c/27554b9505ddfc0aeab466aeb60929dfa17284c7'
tags:
  - cve.org
ingestedAt: '2026-10-18T15:45:12.227Z'
---

## Overview

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

KVM: s390: Fix potential races in dat skey functions

When dat_cond_set_storage_key() finds a large page, it will
conditionally set the storage key in absolute memory using
large_crste_to_phys() to get the absolute address.

There is a race window between dat_entry_walk() and
large_crste_to_phys(): the large page could have been split
concurrently, and large_crste_to_phys() might be called with a crste
that does not designate a large page, leading to crashes.

Similar issues were also present in dat_set_storage_key().

dat_get_storage_key() and dat_reset_reference_bit() did instead check
for a potential concurrent splitting of the large page, but then
handled it incorrectly.

Fix by performing a READ_ONCE on the crste pointer, checking and using
the result, instead of dereferencing the pointer again. In case a race
is detacted, try dat_entry_walk() again.

## Affected

- `Linux >= 8e03e8316eb242af307d1c789d09f1a1457cf9a3 < c958f0498891203fddf2764b28f8b102c6bfd719`
- `Linux >= 8e03e8316eb242af307d1c789d09f1a1457cf9a3 < 27554b9505ddfc0aeab466aeb60929dfa17284c7`
- `Linux 7.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.