---
id: CVE-2026-31482
title: 's390/entry: Scrub r12 register on kernel entry'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  s390/entry: Scrub r12 register on kernel entry

  Before commit f33f2d4c7c80 ("s390/bp: remove TIF_ISOLATE_BP"),
  all entry handlers loaded r12 with the current task point…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 <
    a58d298a83a3a9b7ca99ded9d60a1e77231159ef
  - >-
    Linux >= f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 <
    95c899cd791803a5bf7b73e5994fbbe1cc1a9c36
  - >-
    Linux >= f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 <
    7f4e3233faa8470dd0627bc49b2809f2bfebd909
  - >-
    Linux >= f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 <
    99a8b420f3f0e162eb9c9c9253929d4d23f9bd30
  - >-
    Linux >= f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 <
    0738d395aab8fae3b5a3ad3fc640630c91693c27
  - Linux 6.4
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-05T21:34:38.810147Z'
published: '2026-04-22'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T21:45:01.102Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-31482'
references:
  - url: 'https://git.kernel.org/stable/c/a58d298a83a3a9b7ca99ded9d60a1e77231159ef'
  - url: 'https://git.kernel.org/stable/c/95c899cd791803a5bf7b73e5994fbbe1cc1a9c36'
  - url: 'https://git.kernel.org/stable/c/7f4e3233faa8470dd0627bc49b2809f2bfebd909'
  - url: 'https://git.kernel.org/stable/c/99a8b420f3f0e162eb9c9c9253929d4d23f9bd30'
  - url: 'https://git.kernel.org/stable/c/0738d395aab8fae3b5a3ad3fc640630c91693c27'
tags:
  - cve.org
epss: 0.00122
epssPercentile: 0.01998
ingestedAt: '2026-11-05T22:38:32.149Z'
---

## Overview

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

s390/entry: Scrub r12 register on kernel entry

Before commit f33f2d4c7c80 ("s390/bp: remove TIF_ISOLATE_BP"),
all entry handlers loaded r12 with the current task pointer
(lg %r12,__LC_CURRENT) for use by the BPENTER/BPEXIT macros. That
commit removed TIF_ISOLATE_BP, dropping both the branch prediction
macros and the r12 load, but did not add r12 to the register clearing
sequence.

Add the missing xgr %r12,%r12 to make the register scrub consistent
across all entry points.

## Affected

- `Linux >= f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 < a58d298a83a3a9b7ca99ded9d60a1e77231159ef`
- `Linux >= f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 < 95c899cd791803a5bf7b73e5994fbbe1cc1a9c36`
- `Linux >= f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 < 7f4e3233faa8470dd0627bc49b2809f2bfebd909`
- `Linux >= f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 < 99a8b420f3f0e162eb9c9c9253929d4d23f9bd30`
- `Linux >= f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 < 0738d395aab8fae3b5a3ad3fc640630c91693c27`
- `Linux 6.4`

## Remediation

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