---
id: CVE-2026-98888
title: 'arm64: kprobes: Allow reentering kprobes while single-stepping'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  arm64: kprobes: Allow reentering kprobes while single-stepping

  A kprobe can be hit while another kprobe is in KPROBE_HIT_SS state. This
  can happen when tracing or perf…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    bb0fe9121aa0824211aafa33c7d0151fd25ddb75
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    f96a0606de6bcc8d937b80e6470fd7a174c17e26
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    1f342b3e44c3035a837b53b217d816f7511c0d0a
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    c8e84e292ed4cfc199824146da71bb4397b02a1f
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    68774caca799e9695db56d426c69acebd041c2ed
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    a21bf9cb893126e8d9730995708d0be5eb167652
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    23f851ac0078a908bf3422d6467ebc1db5828c46
  - Linux < 5.10.271
  - Linux < 5.15.222
  - Linux < 6.1.189
  - Linux < 6.6.158
  - Linux < 6.12.111
  - Linux < 6.18.53
  - Linux (all versions)
published: '2026-10-23'
updated: '2026-10-23'
sourceUpdated: '2026-10-23T11:37:46.984Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98888'
references:
  - url: 'https://git.kernel.org/stable/c/bb0fe9121aa0824211aafa33c7d0151fd25ddb75'
  - url: 'https://git.kernel.org/stable/c/f96a0606de6bcc8d937b80e6470fd7a174c17e26'
  - url: 'https://git.kernel.org/stable/c/1f342b3e44c3035a837b53b217d816f7511c0d0a'
  - url: 'https://git.kernel.org/stable/c/c8e84e292ed4cfc199824146da71bb4397b02a1f'
  - url: 'https://git.kernel.org/stable/c/68774caca799e9695db56d426c69acebd041c2ed'
  - url: 'https://git.kernel.org/stable/c/a21bf9cb893126e8d9730995708d0be5eb167652'
  - url: 'https://git.kernel.org/stable/c/23f851ac0078a908bf3422d6467ebc1db5828c46'
tags:
  - cve.org
ingestedAt: '2026-10-23T13:24:55.579Z'
---

## Overview

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

arm64: kprobes: Allow reentering kprobes while single-stepping

A kprobe can be hit while another kprobe is in KPROBE_HIT_SS state. This
can happen when tracing or perf code runs from the debug exception path
while the first kprobe is preparing or executing its out-of-line
single-step instruction.

Currently arm64 treats a kprobe hit in KPROBE_HIT_SS as unrecoverable,
the same as a hit in KPROBE_REENTER. This is too strict. A hit in
KPROBE_HIT_SS is still a one-level reentry and can be handled by saving
the current kprobe state and setting up single-step for the new probe,
just like reentry from KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE.

The truly unrecoverable case is hitting another kprobe while already in
KPROBE_REENTER, because the reentry save area has already been consumed.

Move KPROBE_HIT_SS to the recoverable reentry cases and leave
KPROBE_REENTER as the unrecoverable nested reentry case.

This change also requires saving saved_irqflag in struct prev_kprobe.
When a nested kprobe calls kprobes_save_local_irqflag(), it overwrites
kcb->saved_irqflag with the currently masked DAIF value, losing the
outer kprobe's original DAIF state. Without this fix, when the outer
kprobe's single-step finishes, kprobes_restore_local_irqflag() applies
the wrong DAIF mask and leaves interrupts permanently disabled.

Extend struct prev_kprobe with a saved_irqflag field and save/restore it
alongside kp and status. This ensures the outer kprobe's original
interrupt state is preserved across reentry.

This mirrors the x86 fix in commit 6a5022a56ac3
("kprobes/x86: Allow to handle reentered kprobe on single-stepping").

## Affected

- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < bb0fe9121aa0824211aafa33c7d0151fd25ddb75`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < f96a0606de6bcc8d937b80e6470fd7a174c17e26`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 1f342b3e44c3035a837b53b217d816f7511c0d0a`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < c8e84e292ed4cfc199824146da71bb4397b02a1f`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 68774caca799e9695db56d426c69acebd041c2ed`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < a21bf9cb893126e8d9730995708d0be5eb167652`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 23f851ac0078a908bf3422d6467ebc1db5828c46`
- `Linux < 5.10.271`
- `Linux < 5.15.222`
- `Linux < 6.1.189`
- `Linux < 6.6.158`
- `Linux < 6.12.111`
- `Linux < 6.18.53`
- `Linux (all versions)`

## Remediation

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