GHSA-X383-8HMC-J634

Vulnerability from github – Published: 2025-11-12 12:30 – Updated: 2026-07-30 06:32
VLAI
Details

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.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2025-40167"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-11-12T11:15:47Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: detect invalid INLINE_DATA + EXTENTS flag combination\n\nsyzbot reported a BUG_ON in ext4_es_cache_extent() when opening a verity\nfile on a corrupted ext4 filesystem mounted without a journal.\n\nThe issue is that the filesystem has an inode with both the INLINE_DATA\nand EXTENTS flags set:\n\n    EXT4-fs error (device loop0): ext4_cache_extents:545: inode #15:\n    comm syz.0.17: corrupted extent tree: lblk 0 \u003c prev 66\n\nInvestigation revealed that the inode has both flags set:\n    DEBUG: inode 15 - flag=1, i_inline_off=164, has_inline=1, extents_flag=1\n\nThis is an invalid combination since an inode should have either:\n- INLINE_DATA: data stored directly in the inode\n- EXTENTS: data stored in extent-mapped blocks\n\nHaving both flags causes ext4_has_inline_data() to return true, skipping\nextent tree validation in __ext4_iget(). The unvalidated out-of-order\nextents then trigger a BUG_ON in ext4_es_cache_extent() due to integer\nunderflow when calculating hole sizes.\n\nFix this by detecting this invalid flag combination early in ext4_iget()\nand rejecting the corrupted inode.",
  "id": "GHSA-x383-8hmc-j634",
  "modified": "2026-07-30T06:32:17Z",
  "published": "2025-11-12T12:30:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-40167"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1437c95ab2a28b138d4521653583729f61ccb48b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1d3ad183943b38eec2acf72a0ae98e635dc8456b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1f5ccd22ff482639133f2a0fe08f6d19d0e68717"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2e9e10657b04152ed0d6ecae8d0c02a3405e28f5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4954d297c91d292630ab43ba4d195dc371ce65d3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cb6039b68efa547b676a8a10fc4618d9d1865c23"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/de985264eef64be8a90595908f2e6a87946dad34"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f061f7c331fc16250fc82aa68964f35821687217"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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