---
id: CVE-2026-98043
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: Don't infer non-NULL from a pointer with an unbounded offset

  reg_not_null() decides that a register holds a non-NULL value by
  looking at its type alone
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: Don't infer non-NULL from a pointer with an unbounded offset

  reg_not_null() decides that a register holds a non-NULL value by
  looking at its type alone. For point…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= cac616db39c207dc63465a4e05c6ce0e60b2cce4 <
    cb6642048739bf4ee5aa09fe465511f1e87caa63
  - >-
    Linux >= cac616db39c207dc63465a4e05c6ce0e60b2cce4 <
    67b529f521a6676cdfc78b91b0217d7eaa84216b
  - Linux 5.8
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T11:17:33.090'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-98043'
references:
  - url: 'https://git.kernel.org/stable/c/67b529f521a6676cdfc78b91b0217d7eaa84216b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/cb6642048739bf4ee5aa09fe465511f1e87caa63'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-25T11:06:38.849Z'
---

## Overview

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

bpf: Don't infer non-NULL from a pointer with an unbounded offset

reg_not_null() decides that a register holds a non-NULL value by
looking at its type alone. For pointer types that allow arithmetic the
type only guarantees a non-NULL base, in case of an unbound offset
the runtime offset value might still add up to NULL.
Consider the followng program:

  r6 = bpf_map_lookup_elem(map, &0);  /* present */
  if (r6 == 0) return 0;
  r7 = bpf_map_lookup_elem(map, &1);  /* absent, NULL at runtime */
  r8 = r7;
  r8 -= r6;     /* pointer - pointer: unknown scalar, -r6 */
  r8 <<= 1;
  r8 >>= 1;     /* any non-negative offset is accepted by */
                /* check_reg_sane_offset_ptr() */
  r6 += r8;     /* verifier: map value;    runtime: zero  */
  if (r7 != r6) return 0;
  *(u8 *)(r7 + 0);  /* r7 is inferred non-NULL, both are zero */

At runtime both registers are zero, the comparison is true and the
load faults with NULL pointer dereference.

Require the offset to be within +-BPF_MAX_VAR_OFF in reg_not_null().

## Remediation

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