GHSA-QWVJ-5FWC-QXF7

Vulnerability from github – Published: 2024-05-01 06:31 – Updated: 2024-11-04 18:31
VLAI
Details

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

nilfs2: fix failure to detect DAT corruption in btree and direct mappings

Patch series "nilfs2: fix kernel bug at submit_bh_wbc()".

This resolves a kernel BUG reported by syzbot. Since there are two flaws involved, I've made each one a separate patch.

The first patch alone resolves the syzbot-reported bug, but I think both fixes should be sent to stable, so I've tagged them as such.

This patch (of 2):

Syzbot has reported a kernel bug in submit_bh_wbc() when writing file data to a nilfs2 file system whose metadata is corrupted.

There are two flaws involved in this issue.

The first flaw is that when nilfs_get_block() locates a data block using btree or direct mapping, if the disk address translation routine nilfs_dat_translate() fails with internal code -ENOENT due to DAT metadata corruption, it can be passed back to nilfs_get_block(). This causes nilfs_get_block() to misidentify an existing block as non-existent, causing both data block lookup and insertion to fail inconsistently.

The second flaw is that nilfs_get_block() returns a successful status in this inconsistent state. This causes the caller __block_write_begin_int() or others to request a read even though the buffer is not mapped, resulting in a BUG_ON check for the BH_Mapped flag in submit_bh_wbc() failing.

This fixes the first issue by changing the return value to code -EINVAL when a conversion using DAT fails with code -ENOENT, avoiding the conflicting condition that leads to the kernel bug described above. Here, code -EINVAL indicates that metadata corruption was detected during the block lookup, which will be properly handled as a file system error and converted to -EIO when passing through the nilfs2 bmap layer.

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2024-26956"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-05-01T06:15:11Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnilfs2: fix failure to detect DAT corruption in btree and direct mappings\n\nPatch series \"nilfs2: fix kernel bug at submit_bh_wbc()\".\n\nThis resolves a kernel BUG reported by syzbot.  Since there are two\nflaws involved, I\u0027ve made each one a separate patch.\n\nThe first patch alone resolves the syzbot-reported bug, but I think\nboth fixes should be sent to stable, so I\u0027ve tagged them as such.\n\n\nThis patch (of 2):\n\nSyzbot has reported a kernel bug in submit_bh_wbc() when writing file data\nto a nilfs2 file system whose metadata is corrupted.\n\nThere are two flaws involved in this issue.\n\nThe first flaw is that when nilfs_get_block() locates a data block using\nbtree or direct mapping, if the disk address translation routine\nnilfs_dat_translate() fails with internal code -ENOENT due to DAT metadata\ncorruption, it can be passed back to nilfs_get_block().  This causes\nnilfs_get_block() to misidentify an existing block as non-existent,\ncausing both data block lookup and insertion to fail inconsistently.\n\nThe second flaw is that nilfs_get_block() returns a successful status in\nthis inconsistent state.  This causes the caller __block_write_begin_int()\nor others to request a read even though the buffer is not mapped,\nresulting in a BUG_ON check for the BH_Mapped flag in submit_bh_wbc()\nfailing.\n\nThis fixes the first issue by changing the return value to code -EINVAL\nwhen a conversion using DAT fails with code -ENOENT, avoiding the\nconflicting condition that leads to the kernel bug described above.  Here,\ncode -EINVAL indicates that metadata corruption was detected during the\nblock lookup, which will be properly handled as a file system error and\nconverted to -EIO when passing through the nilfs2 bmap layer.",
  "id": "GHSA-qwvj-5fwc-qxf7",
  "modified": "2024-11-04T18:31:17Z",
  "published": "2024-05-01T06:31:42Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-26956"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2e2619ff5d0def4bb6c2037a32a6eaa28dd95c84"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/46b832e09d43b394ac0f6d9485d2b1a06593f0b7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/82827ca21e7c8a91384c5baa656f78a5adfa4ab4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9cbe1ad5f4354f4df1445e5f4883983328cd6d8e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a8e4d098de1c0f4c5c1f2ed4633a860f0da6d713"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b67189690eb4b7ecc84ae16fa1e880e0123eaa35"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c3b5c5c31e723b568f83d8cafab8629d9d830ffb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f2f26b4a84a0ef41791bd2d70861c8eac748f4ba"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f69e81396aea66304d214f175aa371f1b5578862"
    },
    {
      "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": [
    {
      "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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