---
id: CVE-2026-43416
title: 'powerpc, perf: Check that current->mm is alive before getting user callchain'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  powerpc, perf: Check that current->mm is alive before getting user callchain

  It may happen that mm is already released, which leads to kernel panic.
  This adds the NULL…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 20002ded4d937ca87aca6253b874920a96a763c4 <
    98074e16742ae87fb82e234b419783c5ffc9baea
  - >-
    Linux >= 20002ded4d937ca87aca6253b874920a96a763c4 <
    7e5f60b8cfc02a2b23a40a5f5fd2fa81d010e737
  - >-
    Linux >= 20002ded4d937ca87aca6253b874920a96a763c4 <
    e9bbfb4bfa86c6b5515b868d6982ac60505d7e39
  - Linux 2.6.32
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T15:37:49.414507Z'
published: '2026-05-08'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T15:42:52.602Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-43416'
references:
  - url: 'https://git.kernel.org/stable/c/98074e16742ae87fb82e234b419783c5ffc9baea'
  - url: 'https://git.kernel.org/stable/c/7e5f60b8cfc02a2b23a40a5f5fd2fa81d010e737'
  - url: 'https://git.kernel.org/stable/c/e9bbfb4bfa86c6b5515b868d6982ac60505d7e39'
tags:
  - cve.org
epss: 0.00121
epssPercentile: 0.01901
ingestedAt: '2026-11-06T15:54:03.922Z'
---

## Overview

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

powerpc, perf: Check that current->mm is alive before getting user callchain

It may happen that mm is already released, which leads to kernel panic.
This adds the NULL check for current->mm, similarly to
commit 20afc60f892d ("x86, perf: Check that current->mm is alive before getting user callchain").

I was getting this panic when running a profiling BPF program
(profile.py from bcc-tools):

    [26215.051935] Kernel attempted to read user page (588) - exploit attempt? (uid: 0)
    [26215.051950] BUG: Kernel NULL pointer dereference on read at 0x00000588
    [26215.051952] Faulting instruction address: 0xc00000000020fac0
    [26215.051957] Oops: Kernel access of bad area, sig: 11 [#1]
    [...]
    [26215.052049] Call Trace:
    [26215.052050] [c000000061da6d30] [c00000000020fc10] perf_callchain_user_64+0x2d0/0x490 (unreliable)
    [26215.052054] [c000000061da6dc0] [c00000000020f92c] perf_callchain_user+0x1c/0x30
    [26215.052057] [c000000061da6de0] [c0000000005ab2a0] get_perf_callchain+0x100/0x360
    [26215.052063] [c000000061da6e70] [c000000000573bc8] bpf_get_stackid+0x88/0xf0
    [26215.052067] [c000000061da6ea0] [c008000000042258] bpf_prog_16d4ab9ab662f669_do_perf_event+0xf8/0x274
    [...]

In addition, move storing the top-level stack entry to generic
perf_callchain_user to make sure the top-evel entry is always captured,
even if current->mm is NULL.

[Maddy: fixed message to avoid checkpatch format style error]

## Affected

- `Linux >= 20002ded4d937ca87aca6253b874920a96a763c4 < 98074e16742ae87fb82e234b419783c5ffc9baea`
- `Linux >= 20002ded4d937ca87aca6253b874920a96a763c4 < 7e5f60b8cfc02a2b23a40a5f5fd2fa81d010e737`
- `Linux >= 20002ded4d937ca87aca6253b874920a96a763c4 < e9bbfb4bfa86c6b5515b868d6982ac60505d7e39`
- `Linux 2.6.32`

## Remediation

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