xfs: don't let hidden_space go negative in xfs_metafile_resv_init

{
  "id": "1b6fea3556028b6d9c34be9046949fd52cd04b30883b22486916e6bc2cc16624",
  "url": "https://osv.dev/vulnerability/CVE-2026-98446",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "xfs: don't let hidden_space go negative in xfs_metafile_resv_init",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: xfs: don't let hidden_space go negative in xfs_metafile_resv_init LOLLM points out that if the amount of fdblocks that we can reserve for a metadata btree file goes below the space already used by that file, then the hidden_space subtraction can underflow, causing xfs_dec_fdblocks to subtract a huge amount of space. We never want the target to be less than the used sapce, so fix the logic that adjusts dblocks_avail downwards. Also fix an error in the adjacent comment.",
    "evidence": "osv:CVE-2026-98446",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.55",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.9",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98446",
      "aliases": [
        "CVE-2026-98446"
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      "affected": [
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              "type": "GIT",
              "events": [
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                  "fixed": "930a9c1c321efdaa3e7f8caecb0479cee3baf342"
                },
                {
                  "fixed": "f0d8352a39f4a2e329ae45b71bb0d49e2ca0a6dc"
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                  "fixed": "476582d754cdc5110f806001417fea6c77824c13"
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          "database_specific": {
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        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.15.0"
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                  "fixed": "6.18.55"
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            {
              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.19.0"
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                  "fixed": "7.2.9"
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98446.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:25.895091348Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/476582d754cdc5110f806001417fea6c77824c13",
        "https://git.kernel.org/stable/c/930a9c1c321efdaa3e7f8caecb0479cee3baf342",
        "https://git.kernel.org/stable/c/f0d8352a39f4a2e329ae45b71bb0d49e2ca0a6dc",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98446.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98446",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98446.json"
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    "related_cves": [
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        "value": "CVE-2026-98446",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 492594,
  "published_at": "2026-10-18T15:14:56.724+00:00"
}