---
id: CVE-2026-90195
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args

  On RV64, the ABI requires sign-extension for signed 1-byte and 2-byte kfunc
  args
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args

  On RV64, the ABI requires sign-extension for signed 1-byte and 2-byte kfunc
  args. However, the…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 443574b033876c85a35de4c65c14f7fe092222b2 <
    555fc6f1caf00ce7005e732b688da26c0dc3c5c5
  - >-
    Linux >= 443574b033876c85a35de4c65c14f7fe092222b2 <
    801ae90f8ce099187e6224cec7d72d07a4df0324
  - >-
    Linux >= 443574b033876c85a35de4c65c14f7fe092222b2 <
    71dbd143be598954ae103feadd12692aeb0f2f88
  - >-
    Linux >= 443574b033876c85a35de4c65c14f7fe092222b2 <
    f2aaa621591093cfe8224a25ef2f04a3b1e304b0
  - Linux 6.9
published: '2026-09-17'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T17:17:14.280'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-90195'
references:
  - url: 'https://git.kernel.org/stable/c/555fc6f1caf00ce7005e732b688da26c0dc3c5c5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/71dbd143be598954ae103feadd12692aeb0f2f88'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/801ae90f8ce099187e6224cec7d72d07a4df0324'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f2aaa621591093cfe8224a25ef2f04a3b1e304b0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-17T16:21:47.862Z'
epss: 0.00209
epssPercentile: 0.09807
---

## Overview

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

riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args

On RV64, the ABI requires sign-extension for signed 1-byte and 2-byte kfunc
args. However, the RV64 JIT currently does not perform sign-extension for
such kfunc args.

Before commit 7ce090afbf72 ("bpf: Infer zext_dst based on static register
liveness analysis"), state pruning could potentially omit zero-extension
of 32-bit subregisters, which inadvertently masked the above issue by making
the args appear as if they had been properly sign-extended. After that
commit, the problem is exposed, causing the kfunc_call/kfunc_call_test4
selftest to fail.

Fix this by extending the existing sign-extension logic to handle signed
1-byte and 2-byte kfunc args as well.

## Remediation

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