---
id: CVE-2026-93275
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  perf/x86/intel/pt: Fix stop/start with no update

  If pt_event_stop() is called without PERF_EF_UPDATE flag, then
  perf_aux_output_end() is not called
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  perf/x86/intel/pt: Fix stop/start with no update

  If pt_event_stop() is called without PERF_EF_UPDATE flag, then
  perf_aux_output_end() is not called.  A subsequent call…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 52ca9ced3f70779589e6ecc329baffe69d8f5f7a <
    9b919fb5512f256e9e0604faf960b2bb98aab454
  - >-
    Linux >= 52ca9ced3f70779589e6ecc329baffe69d8f5f7a <
    cab5015ee3f25f789b4a368f2abfa65536576b78
  - >-
    Linux >= 52ca9ced3f70779589e6ecc329baffe69d8f5f7a <
    304844b5545f444d523286da8228a1cbc46ffffa
  - >-
    Linux >= 52ca9ced3f70779589e6ecc329baffe69d8f5f7a <
    2e17bf3a469a41457a3bc31b1f8fd66b6ce94a6d
  - Linux 4.1
published: '2026-09-24'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T16:17:24.667'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-93275'
references:
  - url: 'https://git.kernel.org/stable/c/2e17bf3a469a41457a3bc31b1f8fd66b6ce94a6d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/304844b5545f444d523286da8228a1cbc46ffffa'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9b919fb5512f256e9e0604faf960b2bb98aab454'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/cab5015ee3f25f789b4a368f2abfa65536576b78'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-24T16:47:15.840Z'
epss: 0.00186
epssPercentile: 0.0734
---

## Overview

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

perf/x86/intel/pt: Fix stop/start with no update

If pt_event_stop() is called without PERF_EF_UPDATE flag, then
perf_aux_output_end() is not called.  A subsequent call to pt_event_start()
will call perf_aux_output_begin() again which violates the rule against
nesting and triggers a WARNING in perf_aux_output_begin().

Originally, pt_event_stop() was never called without PERF_EF_UPDATE,
because the only code paths to do so are from event overflow, and Intel PT
does not do that.

However the introduction of group throttling by commit 9734e25fbf5ae
("perf: Fix the throttle logic for a group") meant that an Intel PT event
could be throttled if it was part of a group.  Throttling calls PMU
 ->stop() / ->start() callbacks without flags.

An example is when AUX area sampling is used. The following commands
hit the issue:

  echo 10000 > /proc/sys/kernel/perf_event_max_sample_rate

  perf record -F32000 --aux-sample -e '{intel_pt//u,cycles:u}' \
  -- bash -c 'for i in `seq 1 100000` ; do true ; done'

Use PERF_HES_UPTODATE to track whether perf_aux_output_begin() and
perf_aux_output_end() are balanced.  A cleared PERF_HES_UPTODATE bit
indicates that an AUX output context is still open.

Amend pt_event_start() / pt_event_stop() accordingly so that begin/end
stay balanced:

 - In non-snapshot mode, stop() always closes the buffer (the buffer may
   have run out of space, and that accounting is done by the update), so
   a following start() opens a fresh one as before.

 - In snapshot/overwrite mode, stop() without PERF_EF_UPDATE leaves the
   buffer open so that pt_event_snapshot_aux() can still copy from it,
   and start() then only re-enables tracing instead of calling
   perf_aux_output_begin() again.

Note that pt_event_del() calls pt_event_stop() with PERF_EF_UPDATE flag set
(as is required by the documentation), so a final call to
perf_aux_output_end() is assured.

## Remediation

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