---
id: CVE-2024-44941
title: 'f2fs: fix to cover read extent cache access with lock'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  f2fs: fix to cover read extent cache access with lock

  syzbot reports a f2fs bug as below:

  BUG: KASAN: slab-use-after-free in sanity_check_extent_cache+0x370/0x410 fs/…
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'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 98e4da8ca301e062d79ae168c67e56f3c3de3ce4 <
    9bd5d5e3244242e7be26e86025b74eff3cf20d8c
  - >-
    Linux >= 98e4da8ca301e062d79ae168c67e56f3c3de3ce4 <
    263df78166d3a9609b97d28c34029bd01874cbb8
  - >-
    Linux >= 98e4da8ca301e062d79ae168c67e56f3c3de3ce4 <
    323ef20b5558b9d9fd10c1224327af6f11a8177d
  - >-
    Linux >= 98e4da8ca301e062d79ae168c67e56f3c3de3ce4 <
    d7409b05a64f212735f0d33f5f1602051a886eab
  - Linux 3.8
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2024-09-10T15:27:29.159607Z'
published: '2024-08-26'
updated: '2026-10-30'
sourceUpdated: '2026-10-30T12:19:08.713Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2024-44941'
references:
  - url: 'https://git.kernel.org/stable/c/9bd5d5e3244242e7be26e86025b74eff3cf20d8c'
  - url: 'https://git.kernel.org/stable/c/263df78166d3a9609b97d28c34029bd01874cbb8'
  - url: 'https://git.kernel.org/stable/c/323ef20b5558b9d9fd10c1224327af6f11a8177d'
  - url: 'https://git.kernel.org/stable/c/d7409b05a64f212735f0d33f5f1602051a886eab'
tags:
  - cve.org
epss: 0.00211
epssPercentile: 0.11361
ingestedAt: '2026-11-03T13:45:42.688Z'
---

## Overview

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

f2fs: fix to cover read extent cache access with lock

syzbot reports a f2fs bug as below:

BUG: KASAN: slab-use-after-free in sanity_check_extent_cache+0x370/0x410 fs/f2fs/extent_cache.c:46
Read of size 4 at addr ffff8880739ab220 by task syz-executor200/5097

CPU: 0 PID: 5097 Comm: syz-executor200 Not tainted 6.9.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 sanity_check_extent_cache+0x370/0x410 fs/f2fs/extent_cache.c:46
 do_read_inode fs/f2fs/inode.c:509 [inline]
 f2fs_iget+0x33e1/0x46e0 fs/f2fs/inode.c:560
 f2fs_nfs_get_inode+0x74/0x100 fs/f2fs/super.c:3237
 generic_fh_to_dentry+0x9f/0xf0 fs/libfs.c:1413
 exportfs_decode_fh_raw+0x152/0x5f0 fs/exportfs/expfs.c:444
 exportfs_decode_fh+0x3c/0x80 fs/exportfs/expfs.c:584
 do_handle_to_path fs/fhandle.c:155 [inline]
 handle_to_path fs/fhandle.c:210 [inline]
 do_handle_open+0x495/0x650 fs/fhandle.c:226
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

We missed to cover sanity_check_extent_cache() w/ extent cache lock,
so, below race case may happen, result in use after free issue.

- f2fs_iget
 - do_read_inode
  - f2fs_init_read_extent_tree
  : add largest extent entry in to cache
					- shrink
					 - f2fs_shrink_read_extent_tree
					  - __shrink_extent_tree
					   - __detach_extent_node
					   : drop largest extent entry
  - sanity_check_extent_cache
  : access et->largest w/o lock

let's refactor sanity_check_extent_cache() to avoid extent cache access
and call it before f2fs_init_read_extent_tree() to fix this issue.

## Affected

- `Linux >= 98e4da8ca301e062d79ae168c67e56f3c3de3ce4 < 9bd5d5e3244242e7be26e86025b74eff3cf20d8c`
- `Linux >= 98e4da8ca301e062d79ae168c67e56f3c3de3ce4 < 263df78166d3a9609b97d28c34029bd01874cbb8`
- `Linux >= 98e4da8ca301e062d79ae168c67e56f3c3de3ce4 < 323ef20b5558b9d9fd10c1224327af6f11a8177d`
- `Linux >= 98e4da8ca301e062d79ae168c67e56f3c3de3ce4 < d7409b05a64f212735f0d33f5f1602051a886eab`
- `Linux 3.8`

## Remediation

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