GHSA-V546-2FCJ-RWVX

Vulnerability from github – Published: 2024-08-17 09:30 – Updated: 2026-05-12 12:32
VLAI
Details

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

ext4: make sure the first directory block is not a hole

The syzbot constructs a directory that has no dirblock but is non-inline, i.e. the first directory block is a hole. And no errors are reported when creating files in this directory in the following flow.

ext4_mknod
 ...
  ext4_add_entry
    // Read block 0
    ext4_read_dirblock(dir, block, DIRENT)
      bh = ext4_bread(NULL, inode, block, 0)
      if (!bh && (type == INDEX || type == DIRENT_HTREE))
      // The first directory block is a hole
      // But type == DIRENT, so no error is reported.

After that, we get a directory block without '.' and '..' but with a valid dentry. This may cause some code that relies on dot or dotdot (such as make_indexed_dir()) to crash.

Therefore when ext4_read_dirblock() finds that the first directory block is a hole report that the filesystem is corrupted and return an error to avoid loading corrupted data from disk causing something bad.

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2024-42304"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-08-17T09:15:10Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: make sure the first directory block is not a hole\n\nThe syzbot constructs a directory that has no dirblock but is non-inline,\ni.e. the first directory block is a hole. And no errors are reported when\ncreating files in this directory in the following flow.\n\n    ext4_mknod\n     ...\n      ext4_add_entry\n        // Read block 0\n        ext4_read_dirblock(dir, block, DIRENT)\n          bh = ext4_bread(NULL, inode, block, 0)\n          if (!bh \u0026\u0026 (type == INDEX || type == DIRENT_HTREE))\n          // The first directory block is a hole\n          // But type == DIRENT, so no error is reported.\n\nAfter that, we get a directory block without \u0027.\u0027 and \u0027..\u0027 but with a valid\ndentry. This may cause some code that relies on dot or dotdot (such as\nmake_indexed_dir()) to crash.\n\nTherefore when ext4_read_dirblock() finds that the first directory block\nis a hole report that the filesystem is corrupted and return an error to\navoid loading corrupted data from disk causing something bad.",
  "id": "GHSA-v546-2fcj-rwvx",
  "modified": "2026-05-12T12:32:04Z",
  "published": "2024-08-17T09:30:25Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-42304"
    },
    {
      "type": "WEB",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-265688.html"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/299bc6ffa57e04e74c6cce866d6c0741fb4897a1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9771e3d8365ae1dd5e8846a204cb9af14e3e656a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b609753cbbd38f8c0affd4956c0af178348523ac"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c3893d9de8ee153baac56d127d844103488133b5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d81d7e347d1f1f48a5634607d39eb90c161c8afe"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/de2a011a13a46468a6e8259db58b1b62071fe136"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e02f9941e8c011aa3eafa799def6a134ce06bcfa"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f9ca51596bbfd0f9c386dd1c613c394c78d9e5e6"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2024/10/msg00003.html"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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