GHSA-7XMM-C998-F7C9

Vulnerability from github – Published: 2026-02-14 18:30 – Updated: 2026-03-18 15:30
VLAI
Details

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

flex_proportions: make fprop_new_period() hardirq safe

Bernd has reported a lockdep splat from flexible proportions code that is essentially complaining about the following race:

run_timer_softirq - we are in softirq context call_timer_fn writeout_period fprop_new_period write_seqcount_begin(&p->sequence);

    <hardirq is raised>
    ...
    blk_mq_end_request()
  blk_update_request()
    ext4_end_bio()
      folio_end_writeback()
    __wb_writeout_add()
      __fprop_add_percpu_max()
        if (unlikely(max_frac < FPROP_FRAC_BASE)) {
          fprop_fraction_percpu()
        seq = read_seqcount_begin(&p->sequence);
          - sees odd sequence so loops indefinitely

Note that a deadlock like this is only possible if the bdi has configured maximum fraction of writeout throughput which is very rare in general but frequent for example for FUSE bdis. To fix this problem we have to make sure write section of the sequence counter is irqsafe.

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-2026-23168"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-02-14T16:15:57Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nflex_proportions: make fprop_new_period() hardirq safe\n\nBernd has reported a lockdep splat from flexible proportions code that is\nessentially complaining about the following race:\n\n\u003ctimer fires\u003e\nrun_timer_softirq - we are in softirq context\n  call_timer_fn\n    writeout_period\n      fprop_new_period\n        write_seqcount_begin(\u0026p-\u003esequence);\n\n        \u003chardirq is raised\u003e\n        ...\n        blk_mq_end_request()\n\t  blk_update_request()\n\t    ext4_end_bio()\n\t      folio_end_writeback()\n\t\t__wb_writeout_add()\n\t\t  __fprop_add_percpu_max()\n\t\t    if (unlikely(max_frac \u003c FPROP_FRAC_BASE)) {\n\t\t      fprop_fraction_percpu()\n\t\t\tseq = read_seqcount_begin(\u0026p-\u003esequence);\n\t\t\t  - sees odd sequence so loops indefinitely\n\nNote that a deadlock like this is only possible if the bdi has configured\nmaximum fraction of writeout throughput which is very rare in general but\nfrequent for example for FUSE bdis.  To fix this problem we have to make\nsure write section of the sequence counter is irqsafe.",
  "id": "GHSA-7xmm-c998-f7c9",
  "modified": "2026-03-18T15:30:40Z",
  "published": "2026-02-14T18:30:15Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23168"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0acc9ba7a1b5ba4d998c5753e709be904e179b75"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/78ede9ebd679dadf480dce6f7b798e3603f88348"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/884b2590ffcc7222cbbd6298051f4c243cc36f5d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b91a84299d72ae0e05551e851e47cd3008bd025b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/dd9e2f5b38f1fdd49b1ab6d3a85f81c14369eacc"
    }
  ],
  "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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