---
id: CVE-2022-49170
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  f2fs: fix to do sanity check on curseg->alloc_type

  As Wenqing Liu reported in bugzilla:

  https://bugzilla.kernel.org/show_bug.cgi?id=215657

  - Overview
  UBSAN: array-in…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  f2fs: fix to do sanity check on curseg->alloc_type

  As Wenqing Liu reported in bugzilla:

  https://bugzilla.kernel.org/show_bug.cgi?id=215657

  - Overview
  UBSAN: array-in…
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'
cwe:
  - CWE-129
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 3.8, < 5.10.110'
  - 'linux_kernel >= 5.11, < 5.15.33'
  - 'linux_kernel >= 5.16, < 5.16.19'
  - 'linux_kernel >= 5.17, < 5.17.2'
patched:
  - linux_kernel 5.17.2
published: '2025-02-26'
updated: '2026-08-13'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2022-49170'
references:
  - url: 'https://git.kernel.org/stable/c/0748a0f7dcb9d9dddc80302d73ebcecef6782ef0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/498b7088db71f9707359448cd6800bbb1882f4c3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c12765e3f129b144421c80d3383df885f85ee290'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f41ee8b91c00770d718be2ff4852a80017ae9ab3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f68caedf264a95c0b02dfd0d9f92ac2637d5848a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00275
epssPercentile: 0.20189
ingestedAt: '2026-08-13T00:57:22.842Z'
---

## Overview

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

f2fs: fix to do sanity check on curseg->alloc_type

As Wenqing Liu reported in bugzilla:

https://bugzilla.kernel.org/show_bug.cgi?id=215657

- Overview
UBSAN: array-index-out-of-bounds in fs/f2fs/segment.c:3460:2 when mount and operate a corrupted image

- Reproduce
tested on kernel 5.17-rc4, 5.17-rc6

1. mkdir test_crash
2. cd test_crash
3. unzip tmp2.zip
4. mkdir mnt
5. ./single_test.sh f2fs 2

- Kernel dump
[   46.434454] loop0: detected capacity change from 0 to 131072
[   46.529839] F2FS-fs (loop0): Mounted with checkpoint version = 7548c2d9
[   46.738319] ================================================================================
[   46.738412] UBSAN: array-index-out-of-bounds in fs/f2fs/segment.c:3460:2
[   46.738475] index 231 is out of range for type 'unsigned int [2]'
[   46.738539] CPU: 2 PID: 939 Comm: umount Not tainted 5.17.0-rc6 #1
[   46.738547] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014
[   46.738551] Call Trace:
[   46.738556]  <TASK>
[   46.738563]  dump_stack_lvl+0x47/0x5c
[   46.738581]  ubsan_epilogue+0x5/0x50
[   46.738592]  __ubsan_handle_out_of_bounds+0x68/0x80
[   46.738604]  f2fs_allocate_data_block+0xdff/0xe60 [f2fs]
[   46.738819]  do_write_page+0xef/0x210 [f2fs]
[   46.738934]  f2fs_do_write_node_page+0x3f/0x80 [f2fs]
[   46.739038]  __write_node_page+0x2b7/0x920 [f2fs]
[   46.739162]  f2fs_sync_node_pages+0x943/0xb00 [f2fs]
[   46.739293]  f2fs_write_checkpoint+0x7bb/0x1030 [f2fs]
[   46.739405]  kill_f2fs_super+0x125/0x150 [f2fs]
[   46.739507]  deactivate_locked_super+0x60/0xc0
[   46.739517]  deactivate_super+0x70/0xb0
[   46.739524]  cleanup_mnt+0x11a/0x200
[   46.739532]  __cleanup_mnt+0x16/0x20
[   46.739538]  task_work_run+0x67/0xa0
[   46.739547]  exit_to_user_mode_prepare+0x18c/0x1a0
[   46.739559]  syscall_exit_to_user_mode+0x26/0x40
[   46.739568]  do_syscall_64+0x46/0xb0
[   46.739584]  entry_SYSCALL_64_after_hwframe+0x44/0xae

The root cause is we missed to do sanity check on curseg->alloc_type,
result in out-of-bound accessing on sbi->block_count[] array, fix it.

## Affected

- `linux_kernel >= 3.8, < 5.10.110`
- `linux_kernel >= 5.11, < 5.15.33`
- `linux_kernel >= 5.16, < 5.16.19`
- `linux_kernel >= 5.17, < 5.17.2`

## Remediation

Upgrade past the affected range:

- `linux_kernel 5.17.2`