---
id: CVE-2026-98599
title: 'bpf: Reject non-negative offsets in stack_slot_obj_get_spi()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: Reject non-negative offsets in stack_slot_obj_get_spi()

  bpf_get_spi() computes (-off - 1) / BPF_REG_SIZE using C division,
  which truncates toward zero. For off ==…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 06accc8779c1d558a5b5a21f2ac82b0c95827ddd <
    89a7241fc7ecc1b5e47c3f071081e314523b8d9d
  - >-
    Linux >= 06accc8779c1d558a5b5a21f2ac82b0c95827ddd <
    79a9172f3ab4ad8392c5e5c8944b9b7710ade620
  - Linux 6.4
published: '2026-10-18'
updated: '2026-10-18'
sourceUpdated: '2026-10-18T15:19:11.941Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98599'
references:
  - url: 'https://git.kernel.org/stable/c/89a7241fc7ecc1b5e47c3f071081e314523b8d9d'
  - url: 'https://git.kernel.org/stable/c/79a9172f3ab4ad8392c5e5c8944b9b7710ade620'
tags:
  - cve.org
ingestedAt: '2026-10-18T15:45:12.244Z'
---

## Overview

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

bpf: Reject non-negative offsets in stack_slot_obj_get_spi()

bpf_get_spi() computes (-off - 1) / BPF_REG_SIZE using C division,
which truncates toward zero. For off == 0, this produces spi 0, the
same index used by the valid stack slot at fp-8.

stack_slot_obj_get_spi() currently checks alignment and the resulting
spi bounds, but does not reject the non-negative offset itself. It can
therefore validate a PTR_TO_STACK register holding fp+0 against an
iterator stored at fp-8 even though the runtime receives the actual fp+0
pointer. An effectful iterator kfunc can then interpret memory outside
the BPF stack as iterator state.

Reject non-negative offsets before converting the offset to an spi. All
valid stack objects begin at a negative offset from the frame pointer.

## Affected

- `Linux >= 06accc8779c1d558a5b5a21f2ac82b0c95827ddd < 89a7241fc7ecc1b5e47c3f071081e314523b8d9d`
- `Linux >= 06accc8779c1d558a5b5a21f2ac82b0c95827ddd < 79a9172f3ab4ad8392c5e5c8944b9b7710ade620`
- `Linux 6.4`

## Remediation

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