---
id: CVE-2026-31525
title: 'bpf: Fix undefined behavior in interpreter sdiv/smod for INT_MIN'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: Fix undefined behavior in interpreter sdiv/smod for INT_MIN

  The BPF interpreter's signed 32-bit division and modulo handlers use
  the kernel abs() macro on s32 ope…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= ec0e2da95f72d4a46050a4d994e4fe471474fd80 <
    694ea55f1b1c74f9942d91ec366ae9e822422e42
  - >-
    Linux >= ec0e2da95f72d4a46050a4d994e4fe471474fd80 <
    9ab1227765c446942f290c83382f0b19887c55cf
  - >-
    Linux >= ec0e2da95f72d4a46050a4d994e4fe471474fd80 <
    f14ca604c0ff274fba19f73f1f0485c0047c1396
  - >-
    Linux >= ec0e2da95f72d4a46050a4d994e4fe471474fd80 <
    0d5d8c3ce45c734aaf3c51cbef59155a6746157d
  - >-
    Linux >= ec0e2da95f72d4a46050a4d994e4fe471474fd80 <
    c77b30bd1dcb61f66c640ff7d2757816210c7cb0
  - Linux 6.6
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T15:10:36.308610Z'
exploitAvailable: true
published: '2026-04-22'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T15:20:14.562Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-31525'
references:
  - url: 'https://git.kernel.org/stable/c/694ea55f1b1c74f9942d91ec366ae9e822422e42'
  - url: 'https://git.kernel.org/stable/c/9ab1227765c446942f290c83382f0b19887c55cf'
  - url: 'https://git.kernel.org/stable/c/f14ca604c0ff274fba19f73f1f0485c0047c1396'
  - url: 'https://git.kernel.org/stable/c/0d5d8c3ce45c734aaf3c51cbef59155a6746157d'
  - url: 'https://git.kernel.org/stable/c/c77b30bd1dcb61f66c640ff7d2757816210c7cb0'
tags:
  - cve.org
  - exploit-available
epss: 0.00175
epssPercentile: 0.06549
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/HORKimhab/CVE-2026-31525'
  checkedAt: '2026-10-16T17:25:21.010Z'
ingestedAt: '2026-10-16T17:24:46.659Z'
---

## Overview

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

bpf: Fix undefined behavior in interpreter sdiv/smod for INT_MIN

The BPF interpreter's signed 32-bit division and modulo handlers use
the kernel abs() macro on s32 operands. The abs() macro documentation
(include/linux/math.h) explicitly states the result is undefined when
the input is the type minimum. When DST contains S32_MIN (0x80000000),
abs((s32)DST) triggers undefined behavior and returns S32_MIN unchanged
on arm64/x86. This value is then sign-extended to u64 as
0xFFFFFFFF80000000, causing do_div() to compute the wrong result.

The verifier's abstract interpretation (scalar32_min_max_sdiv) computes
the mathematically correct result for range tracking, creating a
verifier/interpreter mismatch that can be exploited for out-of-bounds
map value access.

Introduce abs_s32() which handles S32_MIN correctly by casting to u32
before negating, avoiding signed overflow entirely. Replace all 8
abs((s32)...) call sites in the interpreter's sdiv32/smod32 handlers.

s32 is the only affected case -- the s64 division/modulo handlers do
not use abs().

## Affected

- `Linux >= ec0e2da95f72d4a46050a4d994e4fe471474fd80 < 694ea55f1b1c74f9942d91ec366ae9e822422e42`
- `Linux >= ec0e2da95f72d4a46050a4d994e4fe471474fd80 < 9ab1227765c446942f290c83382f0b19887c55cf`
- `Linux >= ec0e2da95f72d4a46050a4d994e4fe471474fd80 < f14ca604c0ff274fba19f73f1f0485c0047c1396`
- `Linux >= ec0e2da95f72d4a46050a4d994e4fe471474fd80 < 0d5d8c3ce45c734aaf3c51cbef59155a6746157d`
- `Linux >= ec0e2da95f72d4a46050a4d994e4fe471474fd80 < c77b30bd1dcb61f66c640ff7d2757816210c7cb0`
- `Linux 6.6`

## Remediation

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