---
id: CVE-2026-97918
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  tracing: Undo the registration when enabling the histogram trigger fails

  Commit 6f86bdeab633 ("tracing: Fix bad hist from corrupting named_triggers
  list") described ho…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  tracing: Undo the registration when enabling the histogram trigger fails

  Commit 6f86bdeab633 ("tracing: Fix bad hist from corrupting named_triggers
  list") described ho…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 067fe038e70f6e64960d26a79c4df5f1413d0f13 <
    51b07104d563d4be2be34158d3b9d922ca417642
  - >-
    Linux >= 067fe038e70f6e64960d26a79c4df5f1413d0f13 <
    bfa6bc11aef93a3d9db0ac9564b734849a9d959b
  - >-
    Linux >= 067fe038e70f6e64960d26a79c4df5f1413d0f13 <
    92383cef66791a0c63a2f27755cadbdb2fbf270b
  - Linux 4.17
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T11:17:18.807'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-97918'
references:
  - url: 'https://git.kernel.org/stable/c/51b07104d563d4be2be34158d3b9d922ca417642'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/92383cef66791a0c63a2f27755cadbdb2fbf270b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/bfa6bc11aef93a3d9db0ac9564b734849a9d959b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-25T11:06:38.890Z'
---

## Overview

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

tracing: Undo the registration when enabling the histogram trigger fails

Commit 6f86bdeab633 ("tracing: Fix bad hist from corrupting named_triggers
list") described how a trigger that is registered but not on file->triggers
ends up freed while still on the global named_triggers list, and moved the
registration down so that hist_trigger_enable() follows it immediately. One
path still gets there. hist_trigger_enable() adds the trigger and takes it
straight back out when the event cannot be enabled:

	list_add_tail_rcu(&data->list, &file->triggers);

	update_cond_flag(file);

	if (trace_event_trigger_enable_disable(file, 1) < 0) {
		list_del_rcu(&data->list);
		update_cond_flag(file);
		ret--;
	}

so the list walk in hist_unregister_trigger() matches nothing, test stays
NULL, and the ->free() that would call del_named_trigger() is skipped.
out_unreg falls through to out_free, which frees the trigger anyway:

 BUG: KASAN: slab-use-after-free in find_named_trigger+0xac/0xc0
 Read of size 8 at addr ffff8880091d3160 by task init/1
  find_named_trigger+0xac/0xc0
  hist_register_trigger+0xc1/0xa00
  event_hist_trigger_parse+0x3146/0x6af0
  event_trigger_write+0xce/0x160
 Freed by task 69:
  kfree+0x154/0x420
  trigger_kthread_fn+0xfd/0x160

Leave the trigger where hist_unregister_trigger() can find it and let that
undo the registration, which is the only code that knows all of what
cmd_ops->init() took: the named list entry, the hist_pad reference, the
reference on the trigger a named histogram is shared with, and the copied
cmd_ops. It also pairs the failed trace_event_trigger_enable_disable(),
whose sm_ref and buffered event reference are otherwise left behind.

Since ->free() releases trigger_data and, for a trigger that does not share
its histogram, hist_data with it, out_unreg can no longer fall through to
out_free. For a trigger that does share, hist_register_trigger() has
already destroyed the caller's hist_data, so the fall-through was reading
freed memory there as well.

Move the enable_timestamps check in hist_unregister_trigger() above the
->free() call for the same reason: hist_data does not outlive it once the
trigger being removed is the one that owns it.

## Remediation

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