CVE-2026-97922 (GCVE-0-2026-97922)
Vulnerability from cvelistv5
Published
2026-09-25 10:22
Modified
2026-10-19 09:10
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: tracing: Free histogram var refs regardless of how often they are referenced Using the same variable three or more times in one hist trigger leaks the variable reference and its strings when the trigger is removed. commit 656fe2ba85e8 ("tracing: Use hist trigger's var_ref array to destroy var_refs") made a trigger's var_refs[] array the only owner of a var ref: destroy_hist_field() returns early for HIST_FIELD_FL_VAR_REF, so the field expressions never destroy one. One entry, freed once, no count needed. commit 8bcebc77e85f ("tracing: Fix histogram code when expression has same var as value") then made repeated references share one object and added a count of them. Only the increment side exists, since those expressions still return early and never drop a reference, so __destroy_hist_field() sees how many references were created rather than how many are left. It frees when the decremented count is 0 or 1, so two references work and three or more leak. Sharing kept one array entry per object, and create_var_ref() searches and appends within a single trigger, so nothing outside it holds the object. Removing a trigger whose variables are still referenced is already refused by check_var_refs() with -EBUSY. Drop the count and free unconditionally.
References
Impacted products
Vendor Product Version
Linux Linux Version: 8bcebc77e85f3d7536f96845a0fe94b1dddb6af0
Version: 8bcebc77e85f3d7536f96845a0fe94b1dddb6af0
Version: 8bcebc77e85f3d7536f96845a0fe94b1dddb6af0
Version: 8bcebc77e85f3d7536f96845a0fe94b1dddb6af0
Version: 8bcebc77e85f3d7536f96845a0fe94b1dddb6af0
Version: 8bcebc77e85f3d7536f96845a0fe94b1dddb6af0
Version: ce28d664054df01997baace61d1defca77689798
Version: bf470f051556b610265ea02ad2102de75e8e619c
Version: 4.19.100   ≤
Version: 5.4.16   ≤
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{
  "containers": {
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          "programFiles": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Free histogram var refs regardless of how often they are referenced\n\nUsing the same variable three or more times in one hist trigger leaks the\nvariable reference and its strings when the trigger is removed.\n\ncommit 656fe2ba85e8 (\"tracing: Use hist trigger\u0027s var_ref array to destroy\nvar_refs\") made a trigger\u0027s var_refs[] array the only owner of a var ref:\ndestroy_hist_field() returns early for HIST_FIELD_FL_VAR_REF, so the field\nexpressions never destroy one. One entry, freed once, no count needed.\n\ncommit 8bcebc77e85f (\"tracing: Fix histogram code when expression has same\nvar as value\") then made repeated references share one object and added a\ncount of them. Only the increment side exists, since those expressions\nstill return early and never drop a reference, so __destroy_hist_field()\nsees how many references were created rather than how many are left. It\nfrees when the decremented count is 0 or 1, so two references work and\nthree or more leak.\n\nSharing kept one array entry per object, and create_var_ref() searches and\nappends within a single trigger, so nothing outside it holds the object.\nRemoving a trigger whose variables are still referenced is already refused\nby check_var_refs() with -EBUSY. Drop the count and free unconditionally."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:10:49.154Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a1f1d64a0a9791c842c4646253daf6ac0313eac7"
        },
        {
          "url": "https://git.kernel.org/stable/c/b513a4c60a7aa1f4b4c2a48544ab003cb36f1e94"
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        {
          "url": "https://git.kernel.org/stable/c/e7b6d67b43caee9183a4374d23641578ea556e6c"
        },
        {
          "url": "https://git.kernel.org/stable/c/4cff53bb19412c6f2d90b50678de5c3903f7f96a"
        },
        {
          "url": "https://git.kernel.org/stable/c/94bbd65da4ae26592fa1977a74ee94218ab02a26"
        },
        {
          "url": "https://git.kernel.org/stable/c/4bddcb346a6cf4615ca77f69a589623b877ca267"
        }
      ],
      "title": "tracing: Free histogram var refs regardless of how often they are referenced",
      "x_generator": {
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-97922",
    "datePublished": "2026-09-25T10:22:41.699Z",
    "dateReserved": "2026-09-25T10:18:58.202Z",
    "dateUpdated": "2026-10-19T09:10:49.154Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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