---
id: CVE-2026-97937
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ftrace: fork: Initialize function graph state before copy_exec_state()

  dup_task_struct() copies the parent's task_struct, including ret_stack.
  ftrace_graph_init_task()…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ftrace: fork: Initialize function graph state before copy_exec_state()

  dup_task_struct() copies the parent's task_struct, including ret_stack.
  ftrace_graph_init_task()…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 6b1c66c9cca99bf00386481c7b2aa7394c26d8b8 <
    1fadebbbf31f65beba353fa9d1373bf183e03fed
  - >-
    Linux >= 6b1c66c9cca99bf00386481c7b2aa7394c26d8b8 <
    08cacffeef8f64f1a222c93467ca84f24a46c953
  - Linux 7.2
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T15:18:02.577'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-97937'
references:
  - url: 'https://git.kernel.org/stable/c/08cacffeef8f64f1a222c93467ca84f24a46c953'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/1fadebbbf31f65beba353fa9d1373bf183e03fed'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-25T11:06:38.884Z'
---

## Overview

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

ftrace: fork: Initialize function graph state before copy_exec_state()

dup_task_struct() copies the parent's task_struct, including ret_stack.
ftrace_graph_init_task() clears the copied function graph state, but it
currently runs after copy_exec_state().

For non-CLONE_VM forks, copy_exec_state() allocates a new task_exec_state.
If that allocation fails, copy_process() reaches bad_fork_free and
free_task() calls ftrace_graph_exit_task(). Since the child still carries
the parent's ret_stack pointer, the unwind frees the parent's active
function graph return stack. The parent subsequently accesses freed memory
from function_graph_enter_regs().

KASAN reports:

[   22.190920] ==================================================================
[   22.195899] BUG: KASAN: slab-use-after-free in function_graph_enter_regs+0xa76/0xb90
[   22.200747] Write of size 8 at addr ff110000054dc0a8 by task repro/1
[   22.205134]
[   22.210770] CPU: 0 UID: 0 PID: 1 Comm: repro Not tainted 7.2.0-07732-g9328b3b03bdc-dirty #3 PREEMPT(lazy)
[   22.212576] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[   22.213750] Call Trace:
[   22.215271]  <TASK>
[   22.216242]  ? ftrace_stub_direct_tramp+0x10/0x10
[   22.217774]  dump_stack_lvl+0x4e/0x70
[   22.220531]  print_report+0x157/0x4b4
[   22.223202]  ? fixup_red_left+0x9/0x30
[   22.224407]  ? complete_report_info+0x83/0x110
[   22.226679]  ? function_graph_enter_regs+0xa76/0xb90
[   22.228084]  kasan_report+0xce/0x100
[   22.230109]  ? function_graph_enter_regs+0xa76/0xb90
[   22.232860]  ? stack_trace_save+0x4/0xd0
[   22.234156]  function_graph_enter_regs+0xa76/0xb90
[   22.236090]  ? kasan_save_stack+0x30/0x50
[   22.237752]  ? __pfx_function_graph_enter_regs+0x10/0x10
[   22.238694]  ? ring_buffer_lock_reserve+0x345/0xf80
[   22.239628]  ? stack_trace_save+0x4/0xd0
[   22.242121]  ? stack_trace_save+0x4/0xd0
[   22.243588]  ftrace_graph_func+0xda/0x160
[   22.245362]  ? ftrace_stub_direct_tramp+0x10/0x10
[   22.246520]  0xffffffffa0000095
[   22.250528]  ? stack_trace_save+0x9/0xd0
[   22.251757]  ? ring_buffer_unlock_commit+0x11d/0x5c0
[   22.253152]  stack_trace_save+0x9/0xd0
[   22.254264]  kasan_save_stack+0x30/0x50
[   22.273631]  kasan_save_track+0x14/0x30
[   22.276763]  kasan_save_free_info+0x3b/0x70
[   22.278296]  __kasan_slab_free+0x43/0x70
[   22.280157]  kmem_cache_free+0xbf/0x3b0
[   22.282963]  ? ftrace_stub_direct_tramp+0x10/0x10
[   22.284001]  free_task+0xa2/0x160
[   22.285699]  ? ftrace_stub_direct_tramp+0x10/0x10
[   22.286752]  copy_process+0x2aae/0x7bc0

Initialize the child function graph state immediately after
dup_task_struct(), before the first fallible operation.

## Remediation

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