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smb: client: flush and commit data before querying allocated ranges

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: smb: client: flush and commit data before querying allocated ranges The mode 0 / FALLOC_FL_KEEP_SIZE fallocate emulation for small interior ranges in smb3_simple_fallocate_range() issues FSCTL_QUERY_ALLOCATED_RANGES and zero-fills any sub-range the server reports as an unallocated hole, to force block allocation without changing file contents. This is unsafe against Windows servers. Per the Win32 documentation, FSCTL_QUERY_ALLOCATED_RANGES only reports ranges that *may* contain nonzero data and is explicitly not coherent with recently written data: "a call to FSCTL_QUERY_ALLOCATED_RANGES [after writing to a network file] would not necessarily return a correct list of allocated regions. To ensure coherency [...] flush the data to the file" fsx (generic/363) reproduces the resulting corruption against Windows Server 2022: a range is written, an uncached read returns the data, yet the next FSCTL_QUERY_ALLOCATED_RANGES on that range reports it as a whole hole, so the emulation overwrites live data with zeroes. A network trace confirmed the WRITE, the READ returning data and the query returning an empty range list within microseconds. Samba does not exhibit this; its query is coherent with the written data. Write back the dirty pages, drain any outstanding I/O and issue an SMB2 FLUSH to force the server to commit the data before querying the allocated ranges, so the query reflects the data actually present. With t

Announced Source revision 1
Original source ↗

CVE-2026-98684

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-98684

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
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Prerequisites
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Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "966a3cb7c7db786452a87afdc3b48858fc4d4d6b",
        "lessThan": "f82242fe3109a3ef72f429540b5bdde08fbfb0e4",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "966a3cb7c7db786452a87afdc3b48858fc4d4d6b",
        "lessThan": "bf84e44ff0ed802778eafd7ecb623635379cb506",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "966a3cb7c7db786452a87afdc3b48858fc4d4d6b",
        "lessThan": "aa994489bd835547c191827acc460192e147032d",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c406bb9ece6ef63721daab106f132ff4b4234e81",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "2f9f4a2d0e6fcf0673ed51195e06e47abe966900",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "5e397c943424de94879830e72c95f2679e297a76",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "5.10.50",
        "lessThan": "5.11",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "5.12.17",
        "lessThan": "5.13",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "5.13.2",
        "lessThan": "5.14",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "fs/smb/client/smb2ops.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.14"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.14",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.18.56",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.10",
        "versionType": "semver",
        "lessThanOrEqual": "7.2.*"
      },
      {
        "status": "unaffected",
        "version": "7.3",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "fs/smb/client/smb2ops.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-98684

Source reference: /cveMetadata/cveId

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Event
#38686 · Revision 1
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