---
id: CVE-2025-40167
title: 'ext4: detect invalid INLINE_DATA + EXTENTS flag combination'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ext4: detect invalid INLINE_DATA + EXTENTS flag combination

  syzbot reported a BUG_ON in ext4_es_cache_extent() when opening a verity
  file on a corrupted ext4 filesyste…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e <
    4954d297c91d292630ab43ba4d195dc371ce65d3
  - >-
    Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e <
    f061f7c331fc16250fc82aa68964f35821687217
  - >-
    Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e <
    2e9e10657b04152ed0d6ecae8d0c02a3405e28f5
  - >-
    Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e <
    1437c95ab2a28b138d4521653583729f61ccb48b
  - >-
    Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e <
    cb6039b68efa547b676a8a10fc4618d9d1865c23
  - >-
    Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e <
    de985264eef64be8a90595908f2e6a87946dad34
  - >-
    Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e <
    1f5ccd22ff482639133f2a0fe08f6d19d0e68717
  - >-
    Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e <
    1d3ad183943b38eec2acf72a0ae98e635dc8456b
  - Linux 3.8
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-15T21:57:26.297320Z'
published: '2025-11-12'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T22:02:39.184Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-40167'
references:
  - url: 'https://git.kernel.org/stable/c/4954d297c91d292630ab43ba4d195dc371ce65d3'
  - url: 'https://git.kernel.org/stable/c/f061f7c331fc16250fc82aa68964f35821687217'
  - url: 'https://git.kernel.org/stable/c/2e9e10657b04152ed0d6ecae8d0c02a3405e28f5'
  - url: 'https://git.kernel.org/stable/c/1437c95ab2a28b138d4521653583729f61ccb48b'
  - url: 'https://git.kernel.org/stable/c/cb6039b68efa547b676a8a10fc4618d9d1865c23'
  - url: 'https://git.kernel.org/stable/c/de985264eef64be8a90595908f2e6a87946dad34'
  - url: 'https://git.kernel.org/stable/c/1f5ccd22ff482639133f2a0fe08f6d19d0e68717'
  - url: 'https://git.kernel.org/stable/c/1d3ad183943b38eec2acf72a0ae98e635dc8456b'
tags:
  - cve.org
epss: 0.00165
epssPercentile: 0.05404
ingestedAt: '2026-10-15T22:48:25.548Z'
---

## Overview

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

ext4: detect invalid INLINE_DATA + EXTENTS flag combination

syzbot reported a BUG_ON in ext4_es_cache_extent() when opening a verity
file on a corrupted ext4 filesystem mounted without a journal.

The issue is that the filesystem has an inode with both the INLINE_DATA
and EXTENTS flags set:

    EXT4-fs error (device loop0): ext4_cache_extents:545: inode #15:
    comm syz.0.17: corrupted extent tree: lblk 0 < prev 66

Investigation revealed that the inode has both flags set:
    DEBUG: inode 15 - flag=1, i_inline_off=164, has_inline=1, extents_flag=1

This is an invalid combination since an inode should have either:
- INLINE_DATA: data stored directly in the inode
- EXTENTS: data stored in extent-mapped blocks

Having both flags causes ext4_has_inline_data() to return true, skipping
extent tree validation in __ext4_iget(). The unvalidated out-of-order
extents then trigger a BUG_ON in ext4_es_cache_extent() due to integer
underflow when calculating hole sizes.

Fix this by detecting this invalid flag combination early in ext4_iget()
and rejecting the corrupted inode.

## Affected

- `Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e < 4954d297c91d292630ab43ba4d195dc371ce65d3`
- `Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e < f061f7c331fc16250fc82aa68964f35821687217`
- `Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e < 2e9e10657b04152ed0d6ecae8d0c02a3405e28f5`
- `Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e < 1437c95ab2a28b138d4521653583729f61ccb48b`
- `Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e < cb6039b68efa547b676a8a10fc4618d9d1865c23`
- `Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e < de985264eef64be8a90595908f2e6a87946dad34`
- `Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e < 1f5ccd22ff482639133f2a0fe08f6d19d0e68717`
- `Linux >= f19d5870cbf72d4cb2a8e1f749dff97af99b071e < 1d3ad183943b38eec2acf72a0ae98e635dc8456b`
- `Linux 3.8`

## Remediation

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