CVE-2026-23177 (GCVE-0-2026-23177)
Vulnerability from cvelistv5
Published
2026-02-14 16:27
Modified
2026-02-14 16:27
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: mm, shmem: prevent infinite loop on truncate race When truncating a large swap entry, shmem_free_swap() returns 0 when the entry's index doesn't match the given index due to lookup alignment. The failure fallback path checks if the entry crosses the end border and aborts when it happens, so truncate won't erase an unexpected entry or range. But one scenario was ignored. When `index` points to the middle of a large swap entry, and the large swap entry doesn't go across the end border, find_get_entries() will return that large swap entry as the first item in the batch with `indices[0]` equal to `index`. The entry's base index will be smaller than `indices[0]`, so shmem_free_swap() will fail and return 0 due to the "base < index" check. The code will then call shmem_confirm_swap(), get the order, check if it crosses the END boundary (which it doesn't), and retry with the same index. The next iteration will find the same entry again at the same index with same indices, leading to an infinite loop. Fix this by retrying with a round-down index, and abort if the index is smaller than the truncate range.
References
Impacted products
Vendor Product Version
Linux Linux Version: 809bc86517cc408b5b8cb8e08e69096639432bc8
Version: 809bc86517cc408b5b8cb8e08e69096639432bc8
Version: 809bc86517cc408b5b8cb8e08e69096639432bc8
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "mm/shmem.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "dfc3ab6bd64860f8022d69903be299d09be86e11",
              "status": "affected",
              "version": "809bc86517cc408b5b8cb8e08e69096639432bc8",
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          "programFiles": [
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          ],
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          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.12"
            },
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              "lessThan": "6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.70",
              "versionType": "semver"
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            {
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              "status": "unaffected",
              "version": "6.18.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.19",
              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "cpeApplicability": [
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              "cpeMatch": [
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                  "versionStartIncluding": "6.12",
                  "vulnerable": true
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
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          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm, shmem: prevent infinite loop on truncate race\n\nWhen truncating a large swap entry, shmem_free_swap() returns 0 when the\nentry\u0027s index doesn\u0027t match the given index due to lookup alignment.  The\nfailure fallback path checks if the entry crosses the end border and\naborts when it happens, so truncate won\u0027t erase an unexpected entry or\nrange.  But one scenario was ignored.\n\nWhen `index` points to the middle of a large swap entry, and the large\nswap entry doesn\u0027t go across the end border, find_get_entries() will\nreturn that large swap entry as the first item in the batch with\n`indices[0]` equal to `index`.  The entry\u0027s base index will be smaller\nthan `indices[0]`, so shmem_free_swap() will fail and return 0 due to the\n\"base \u003c index\" check.  The code will then call shmem_confirm_swap(), get\nthe order, check if it crosses the END boundary (which it doesn\u0027t), and\nretry with the same index.\n\nThe next iteration will find the same entry again at the same index with\nsame indices, leading to an infinite loop.\n\nFix this by retrying with a round-down index, and abort if the index is\nsmaller than the truncate range."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-02-14T16:27:09.429Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/dfc3ab6bd64860f8022d69903be299d09be86e11"
        },
        {
          "url": "https://git.kernel.org/stable/c/7b6a0f121d50234aab3e7ab9a62ebe826d40a32a"
        },
        {
          "url": "https://git.kernel.org/stable/c/2030dddf95451b4e7a389f052091e7c4b7b274c6"
        }
      ],
      "title": "mm, shmem: prevent infinite loop on truncate race",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23177",
    "datePublished": "2026-02-14T16:27:09.429Z",
    "dateReserved": "2026-01-13T15:37:45.983Z",
    "dateUpdated": "2026-02-14T16:27:09.429Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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