CVE-2026-97922 (GCVE-0-2026-97922)

Vulnerability from cvelistv5 – Published: 2026-09-25 10:22 – Updated: 2026-09-25 10:22
VLAI
Title
tracing: Free histogram var refs regardless of how often they are referenced
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.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 8bcebc77e85f3d7536f96845a0fe94b1dddb6af0 , < e7b6d67b43caee9183a4374d23641578ea556e6c (git)
Affected: 8bcebc77e85f3d7536f96845a0fe94b1dddb6af0 , < 4cff53bb19412c6f2d90b50678de5c3903f7f96a (git)
Affected: 8bcebc77e85f3d7536f96845a0fe94b1dddb6af0 , < 94bbd65da4ae26592fa1977a74ee94218ab02a26 (git)
Affected: 8bcebc77e85f3d7536f96845a0fe94b1dddb6af0 , < 4bddcb346a6cf4615ca77f69a589623b877ca267 (git)
Affected: ce28d664054df01997baace61d1defca77689798 (git)
Affected: bf470f051556b610265ea02ad2102de75e8e619c (git)
Affected: 4.19.100 , < 4.20 (semver)
Affected: 5.4.16 , < 5.5 (semver)
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Linux Linux Affected: 5.5
Unaffected: 0 , < 5.5 (semver)
Unaffected: 6.12.111 , ≤ 6.12.* (semver)
Unaffected: 6.18.53 , ≤ 6.18.* (semver)
Unaffected: 7.2.7 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc3 , ≤ * (original_commit_for_fix)
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          "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."
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        "dateUpdated": "2026-09-25T10:22:41.699Z",
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        "shortName": "Linux"
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    "dateReserved": "2026-09-25T10:18:58.202Z",
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            "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."
          }
        ],
        "id": "CVE-2026-97922",
        "lastModified": "2026-09-25T11:17:19.287",
        "metrics": {},
        "published": "2026-09-25T11:17:19.287",
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.