---
id: CVE-2026-98380
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: reject IDR error pointers when deleting actions

  tcf_action_delete() drops the reference held by its lookup before calling
  tcf_idr_delete_index() with the sa…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: reject IDR error pointers when deleting actions

  tcf_action_delete() drops the reference held by its lookup before calling
  tcf_idr_delete_index() with the sa…
severity: none
published: '2026-10-09'
updated: '2026-10-09'
sourceUpdated: '2026-10-09T08:16:56.400'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-98380'
references:
  - url: 'https://git.kernel.org/stable/c/259caa711b7688365676442e2fdb286b8aceaa80'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/39b751a210bf61a374afa82749afc7a77a08bf1d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6bf076258aac4e0af69ef317656c31ce6444d647'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6c9f07bf8800171de2cd3f02815cebe1f4d45f2d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/968550a439f64bd1a6c0d88efb92e4f082f84a26'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a9551f26287debe6d8aa6e8841974661065b975f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c82b797abe668d0b668601a93ba2c0b071a63574'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/dd80a7519824b72c8fcfd3cc50cb93f7e2d90923'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
ingestedAt: '2026-10-09T08:29:41.351Z'
---

## Overview

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

net/sched: reject IDR error pointers when deleting actions

tcf_action_delete() drops the reference held by its lookup before calling
tcf_idr_delete_index() with the saved action index.  An unlocked
classifier can remove that action and reserve the same IDR slot with
ERR_PTR(-EBUSY) in between.

tcf_idr_delete_index() only checks the lookup result for NULL.  It
therefore treats the reservation as a tc_action and dereferences
tcfa_bindcnt.  A hardware execution breakpoint was used to schedule the
interleaving without changing the kernel source.  KASAN reported this
decoded trace:

  BUG: KASAN: null-ptr-deref in tca_action_gd+0x5b9/0x1010
  Read of size 4 at addr 0000000000000010 by task poc/150
  Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002
  RIP: tca_action_gd+0x5c0/0x1010:
    arch_atomic_read at arch/x86/include/asm/atomic.h:23
    raw_atomic_read at include/linux/atomic/atomic-arch-fallback.h:457
    atomic_read at include/linux/atomic/atomic-instrumented.h:33
    tcf_idr_delete_index at net/sched/act_api.c:766
    tcf_action_delete at net/sched/act_api.c:1859
    tcf_del_notify at net/sched/act_api.c:2014
    tca_action_gd at net/sched/act_api.c:2064
  R13: 0000000000000010 R15: fffffffffffffff0
  Kernel panic - not syncing: Fatal exception

R15 contains ERR_PTR(-EBUSY), and adding the tcfa_bindcnt offset produces
the address in R13.  With the guard applied, the same reproducer returned
-ENOENT without a KASAN report or panic.  Treat error pointers as absent
and return -ENOENT.

## Remediation

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