ghsa-cwr2-26gq-v2xr
Vulnerability from github
Published
2024-04-03 15:30
Modified
2024-06-27 15:30
Details

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

nilfs2: fix hang in nilfs_lookup_dirty_data_buffers()

Syzbot reported a hang issue in migrate_pages_batch() called by mbind() and nilfs_lookup_dirty_data_buffers() called in the log writer of nilfs2.

While migrate_pages_batch() locks a folio and waits for the writeback to complete, the log writer thread that should bring the writeback to completion picks up the folio being written back in nilfs_lookup_dirty_data_buffers() that it calls for subsequent log creation and was trying to lock the folio. Thus causing a deadlock.

In the first place, it is unexpected that folios/pages in the middle of writeback will be updated and become dirty. Nilfs2 adds a checksum to verify the validity of the log being written and uses it for recovery at mount, so data changes during writeback are suppressed. Since this is broken, an unclean shutdown could potentially cause recovery to fail.

Investigation revealed that the root cause is that the wait for writeback completion in nilfs_page_mkwrite() is conditional, and if the backing device does not require stable writes, data may be modified without waiting.

Fix these issues by making nilfs_page_mkwrite() wait for writeback to finish regardless of the stable write requirement of the backing device.

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{
  "affected": [],
  "aliases": [
    "CVE-2024-26696"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-04-03T15:15:52Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnilfs2: fix hang in nilfs_lookup_dirty_data_buffers()\n\nSyzbot reported a hang issue in migrate_pages_batch() called by mbind()\nand nilfs_lookup_dirty_data_buffers() called in the log writer of nilfs2.\n\nWhile migrate_pages_batch() locks a folio and waits for the writeback to\ncomplete, the log writer thread that should bring the writeback to\ncompletion picks up the folio being written back in\nnilfs_lookup_dirty_data_buffers() that it calls for subsequent log\ncreation and was trying to lock the folio.  Thus causing a deadlock.\n\nIn the first place, it is unexpected that folios/pages in the middle of\nwriteback will be updated and become dirty.  Nilfs2 adds a checksum to\nverify the validity of the log being written and uses it for recovery at\nmount, so data changes during writeback are suppressed.  Since this is\nbroken, an unclean shutdown could potentially cause recovery to fail.\n\nInvestigation revealed that the root cause is that the wait for writeback\ncompletion in nilfs_page_mkwrite() is conditional, and if the backing\ndevice does not require stable writes, data may be modified without\nwaiting.\n\nFix these issues by making nilfs_page_mkwrite() wait for writeback to\nfinish regardless of the stable write requirement of the backing device.",
  "id": "GHSA-cwr2-26gq-v2xr",
  "modified": "2024-06-27T15:30:38Z",
  "published": "2024-04-03T15:30:42Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-26696"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/228742b2ddfb99dfd71e5a307e6088ab6836272e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/38296afe3c6ee07319e01bb249aa4bb47c07b534"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7e9b622bd0748cc104d66535b76d9b3535f9dc0f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8494ba2c9ea00a54d5b50e69b22c55a8958bce32"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/862ee4422c38be5c249844a684b00d0dbe9d1e46"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/98a4026b22ff440c7f47056481bcbbe442f607d6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e38585401d464578d30f5868ff4ca54475c34f7d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ea5ddbc11613b55e5128c85f57b08f907abd9b28"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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