---
id: CVE-2024-49926
title: >-
  rcu-tasks: Fix access non-existent percpu rtpcp variable in
  rcu_tasks_need_gpcb()
summary: >-
  In the Linux kernel, the following vulnerability has been resolved:


  rcu-tasks: Fix access non-existent percpu rtpcp variable in
  rcu_tasks_need_gpcb()


  For kernels built with CONFIG_FORCE_NR_CPUS=y, the nr_cpu_ids is

  defined as NR_CPUS i…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 8610b65680390a103b58f46282a1b05f7eebbba4 <
    a89f6e90e64ecadd19f32bb8128d22b518bd656c
  - >-
    Linux >= 8610b65680390a103b58f46282a1b05f7eebbba4 <
    b3b2431ed27f4ebc28e26cdf005c1de42dc60bdf
  - >-
    Linux >= 8610b65680390a103b58f46282a1b05f7eebbba4 <
    3104bddc666ff64b90491868bbc4c7ebdd90aedf
  - >-
    Linux >= 8610b65680390a103b58f46282a1b05f7eebbba4 <
    05095271a4fb0f6497121a057f9a2edf386d5d96
  - >-
    Linux >= 8610b65680390a103b58f46282a1b05f7eebbba4 <
    fd70e9f1d85f5323096ad313ba73f5fe3d15ea41
  - Linux 5.17
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2024-10-22T13:39:42.362013Z'
published: '2024-10-21'
updated: '2026-10-30'
sourceUpdated: '2026-10-30T12:19:43.730Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2024-49926'
references:
  - url: 'https://git.kernel.org/stable/c/a89f6e90e64ecadd19f32bb8128d22b518bd656c'
  - url: 'https://git.kernel.org/stable/c/b3b2431ed27f4ebc28e26cdf005c1de42dc60bdf'
  - url: 'https://git.kernel.org/stable/c/3104bddc666ff64b90491868bbc4c7ebdd90aedf'
  - url: 'https://git.kernel.org/stable/c/05095271a4fb0f6497121a057f9a2edf386d5d96'
  - url: 'https://git.kernel.org/stable/c/fd70e9f1d85f5323096ad313ba73f5fe3d15ea41'
tags:
  - cve.org
epss: 0.00235
epssPercentile: 0.14493
ingestedAt: '2026-11-03T14:47:02.508Z'
---

## Overview

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

rcu-tasks: Fix access non-existent percpu rtpcp variable in rcu_tasks_need_gpcb()

For kernels built with CONFIG_FORCE_NR_CPUS=y, the nr_cpu_ids is
defined as NR_CPUS instead of the number of possible cpus, this
will cause the following system panic:

smpboot: Allowing 4 CPUs, 0 hotplug CPUs
...
setup_percpu: NR_CPUS:512 nr_cpumask_bits:512 nr_cpu_ids:512 nr_node_ids:1
...
BUG: unable to handle page fault for address: ffffffff9911c8c8
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 0 PID: 15 Comm: rcu_tasks_trace Tainted: G W
6.6.21 #1 5dc7acf91a5e8e9ac9dcfc35bee0245691283ea6
RIP: 0010:rcu_tasks_need_gpcb+0x25d/0x2c0
RSP: 0018:ffffa371c00a3e60 EFLAGS: 00010082
CR2: ffffffff9911c8c8 CR3: 000000040fa20005 CR4: 00000000001706f0
Call Trace:
<TASK>
? __die+0x23/0x80
? page_fault_oops+0xa4/0x180
? exc_page_fault+0x152/0x180
? asm_exc_page_fault+0x26/0x40
? rcu_tasks_need_gpcb+0x25d/0x2c0
? __pfx_rcu_tasks_kthread+0x40/0x40
rcu_tasks_one_gp+0x69/0x180
rcu_tasks_kthread+0x94/0xc0
kthread+0xe8/0x140
? __pfx_kthread+0x40/0x40
ret_from_fork+0x34/0x80
? __pfx_kthread+0x40/0x40
ret_from_fork_asm+0x1b/0x80
</TASK>

Considering that there may be holes in the CPU numbers, use the
maximum possible cpu number, instead of nr_cpu_ids, for configuring
enqueue and dequeue limits.

[ neeraj.upadhyay: Fix htmldocs build error reported by Stephen Rothwell ]

## Affected

- `Linux >= 8610b65680390a103b58f46282a1b05f7eebbba4 < a89f6e90e64ecadd19f32bb8128d22b518bd656c`
- `Linux >= 8610b65680390a103b58f46282a1b05f7eebbba4 < b3b2431ed27f4ebc28e26cdf005c1de42dc60bdf`
- `Linux >= 8610b65680390a103b58f46282a1b05f7eebbba4 < 3104bddc666ff64b90491868bbc4c7ebdd90aedf`
- `Linux >= 8610b65680390a103b58f46282a1b05f7eebbba4 < 05095271a4fb0f6497121a057f9a2edf386d5d96`
- `Linux >= 8610b65680390a103b58f46282a1b05f7eebbba4 < fd70e9f1d85f5323096ad313ba73f5fe3d15ea41`
- `Linux 5.17`

## Remediation

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