ghsa-xq4m-hfgr-r2x5
Vulnerability from github
Published
2024-04-03 15:30
Modified
2024-11-07 18:31
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Details

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

nilfs2: fix potential bug in end_buffer_async_write

According to a syzbot report, end_buffer_async_write(), which handles the completion of block device writes, may detect abnormal condition of the buffer async_write flag and cause a BUG_ON failure when using nilfs2.

Nilfs2 itself does not use end_buffer_async_write(). But, the async_write flag is now used as a marker by commit 7f42ec394156 ("nilfs2: fix issue with race condition of competition between segments for dirty blocks") as a means of resolving double list insertion of dirty blocks in nilfs_lookup_dirty_data_buffers() and nilfs_lookup_node_buffers() and the resulting crash.

This modification is safe as long as it is used for file data and b-tree node blocks where the page caches are independent. However, it was irrelevant and redundant to also introduce async_write for segment summary and super root blocks that share buffers with the backing device. This led to the possibility that the BUG_ON check in end_buffer_async_write would fail as described above, if independent writebacks of the backing device occurred in parallel.

The use of async_write for segment summary buffers has already been removed in a previous change.

Fix this issue by removing the manipulation of the async_write flag for the remaining super root block buffer.

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{
  "affected": [],
  "aliases": [
    "CVE-2024-26685"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-04-03T15:15:52Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnilfs2: fix potential bug in end_buffer_async_write\n\nAccording to a syzbot report, end_buffer_async_write(), which handles the\ncompletion of block device writes, may detect abnormal condition of the\nbuffer async_write flag and cause a BUG_ON failure when using nilfs2.\n\nNilfs2 itself does not use end_buffer_async_write().  But, the async_write\nflag is now used as a marker by commit 7f42ec394156 (\"nilfs2: fix issue\nwith race condition of competition between segments for dirty blocks\") as\na means of resolving double list insertion of dirty blocks in\nnilfs_lookup_dirty_data_buffers() and nilfs_lookup_node_buffers() and the\nresulting crash.\n\nThis modification is safe as long as it is used for file data and b-tree\nnode blocks where the page caches are independent.  However, it was\nirrelevant and redundant to also introduce async_write for segment summary\nand super root blocks that share buffers with the backing device.  This\nled to the possibility that the BUG_ON check in end_buffer_async_write\nwould fail as described above, if independent writebacks of the backing\ndevice occurred in parallel.\n\nThe use of async_write for segment summary buffers has already been\nremoved in a previous change.\n\nFix this issue by removing the manipulation of the async_write flag for\nthe remaining super root block buffer.",
  "id": "GHSA-xq4m-hfgr-r2x5",
  "modified": "2024-11-07T18:31:20Z",
  "published": "2024-04-03T15:30:42Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-26685"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2c3bdba00283a6c7a5b19481a59a730f46063803"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5bc09b397cbf1221f8a8aacb1152650c9195b02b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/626daab3811b772086aef1bf8eed3ffe6f523eff"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6589f0f72f8edd1fa11adce4eedbd3615f2e78ab"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8fa90634ec3e9cc50f42dd605eec60f2d146ced8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c4a09fdac625e64abe478dcf88bfa20406616928"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d31c8721e816eff5ca6573cc487754f357c093cd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f3e4963566f58726d3265a727116a42b591f6596"
    },
    {
      "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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