---
id: CVE-2026-98800
title: 'bpf: Wait for an RCU tasks grace period before freeing trampoline progs'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: Wait for an RCU tasks grace period before freeing trampoline progs

  When a prog is detached from a trampoline, it is freed after an RCU
  grace period, or an RCU tas…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= e21aa341785c679dd409c8cb71f864c00fe6c463 <
    40955f6512a03f0e046f5256b0706b26ba191018
  - >-
    Linux >= e21aa341785c679dd409c8cb71f864c00fe6c463 <
    0fb5751a6e411b1b466c06e50021818d9391df98
  - Linux e21d2b92354b3cd25dd774ebb0f0e52ff04a7861
  - Linux 85d177f56e5256e14b74a65940f981f6e3e8bb32
  - Linux >= 5.10.28 < 5.11
  - Linux >= 5.11.11 < 5.12
  - Linux 5.12
published: '2026-10-18'
updated: '2026-10-18'
sourceUpdated: '2026-10-18T15:48:46.223Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98800'
references:
  - url: 'https://git.kernel.org/stable/c/40955f6512a03f0e046f5256b0706b26ba191018'
  - url: 'https://git.kernel.org/stable/c/0fb5751a6e411b1b466c06e50021818d9391df98'
tags:
  - cve.org
ingestedAt: '2026-10-18T16:47:32.482Z'
---

## Overview

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

bpf: Wait for an RCU tasks grace period before freeing trampoline progs

When a prog is detached from a trampoline, it is freed after an RCU
grace period, or an RCU tasks trace one if it is sleepable. This covers
the tasks that are running the prog, since the prog's enter helper takes
the matching read lock before the prog is called. On a preemptible
kernel, it doesn't cover a task that was preempted in the trampoline
just before the enter helper. That task holds no lock yet, and it calls
the prog after it was freed:

  BUG: KASAN: vmalloc-out-of-bounds in __bpf_prog_enter_recur+0x3a5/0x3f0
  Read of size 8 at addr ffffc90000055040 by task candidate/110
  CPU: 1 UID: 0 PID: 110 Comm: candidate Not tainted 7.3.0-rc2-00014-g15071f2a1263-dirty #2 PREEMPT(full)
  Call Trace:
   <TASK>
   __bpf_prog_enter_recur+0x3a5/0x3f0
   bpf_trampoline_6442509193+0x37/0xf1
   __x64_sys_futex+0x9/0x410
   do_syscall_64+0xb0/0x530
   ...

Wait for an RCU tasks grace period before the existing one when freeing
a prog that was linked to a trampoline. An RCU tasks grace period only
ends once the tasks that were preempted have run again, and
bpf_tramp_image_put() already relies on it to free the image. It doesn't
wait for tasks that sleep in the trampoline, the next commit takes care
of those.

Only progs that were linked to a trampoline can be called this way, so
bpf_trampoline_add_prog() marks them and other progs are still freed as
before.

## Affected

- `Linux >= e21aa341785c679dd409c8cb71f864c00fe6c463 < 40955f6512a03f0e046f5256b0706b26ba191018`
- `Linux >= e21aa341785c679dd409c8cb71f864c00fe6c463 < 0fb5751a6e411b1b466c06e50021818d9391df98`
- `Linux e21d2b92354b3cd25dd774ebb0f0e52ff04a7861`
- `Linux 85d177f56e5256e14b74a65940f981f6e3e8bb32`
- `Linux >= 5.10.28 < 5.11`
- `Linux >= 5.11.11 < 5.12`
- `Linux 5.12`

## Remediation

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