CVE-2026-23248 (GCVE-0-2026-23248)

Vulnerability from cvelistv5 – Published: 2026-03-18 10:05 – Updated: 2026-05-11 22:03
VLAI
Title
perf/core: Fix refcount bug and potential UAF in perf_mmap
Summary
In the Linux kernel, the following vulnerability has been resolved: perf/core: Fix refcount bug and potential UAF in perf_mmap Syzkaller reported a refcount_t: addition on 0; use-after-free warning in perf_mmap. The issue is caused by a race condition between a failing mmap() setup and a concurrent mmap() on a dependent event (e.g., using output redirection). In perf_mmap(), the ring_buffer (rb) is allocated and assigned to event->rb with the mmap_mutex held. The mutex is then released to perform map_range(). If map_range() fails, perf_mmap_close() is called to clean up. However, since the mutex was dropped, another thread attaching to this event (via inherited events or output redirection) can acquire the mutex, observe the valid event->rb pointer, and attempt to increment its reference count. If the cleanup path has already dropped the reference count to zero, this results in a use-after-free or refcount saturation warning. Fix this by extending the scope of mmap_mutex to cover the map_range() call. This ensures that the ring buffer initialization and mapping (or cleanup on failure) happens atomically effectively, preventing other threads from accessing a half-initialized or dying ring buffer.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: b709eb872e19a19607bbb6d2975bc264d59735cf , < c27dea9f50ed525facb62ef647dddc4722456e07 (git)
Affected: b709eb872e19a19607bbb6d2975bc264d59735cf , < ac7ecb65af170a7fc193e7bd8be15dac84ec6a56 (git)
Affected: b709eb872e19a19607bbb6d2975bc264d59735cf , < 77de62ad3de3967818c3dbe656b7336ebee461d2 (git)
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Linux Linux Affected: 6.14
Unaffected: 0 , < 6.14 (semver)
Unaffected: 6.18.17 , ≤ 6.18.* (semver)
Unaffected: 6.19.7 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
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The mutex is then released to\\nperform map_range().\\n\\nIf map_range() fails, perf_mmap_close() is called to clean up.\\nHowever, since the mutex was dropped, another thread attaching to\\nthis event (via inherited events or output redirection) can acquire\\nthe mutex, observe the valid event-\u003erb pointer, and attempt to\\nincrement its reference count. If the cleanup path has already\\ndropped the reference count to zero, this results in a\\nuse-after-free or refcount saturation warning.\\n\\nFix this by extending the scope of mmap_mutex to cover the\\nmap_range() call. 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Esto asegura que la inicializaci\u00f3n y el mapeo del b\u00fafer de anillo (o la limpieza en caso de fallo) ocurra de manera at\u00f3mica y efectiva, evitando que otros hilos accedan a un b\u00fafer de anillo medio inicializado o en proceso de terminaci\u00f3n.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-416\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.14\",\"versionEndExcluding\":\"6.18.17\",\"matchCriteriaId\":\"E367EC2E-72DB-4555-9BE2-A5B9C97AD4E6\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.19\",\"versionEndExcluding\":\"6.19.7\",\"matchCriteriaId\":\"69245D10-0B71-485E-80C3-A64F077004D3\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"F253B622-8837-4245-BCE5-A7BF8FC76A16\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/77de62ad3de3967818c3dbe656b7336ebee461d2\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/ac7ecb65af170a7fc193e7bd8be15dac84ec6a56\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/c27dea9f50ed525facb62ef647dddc4722456e07\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}"
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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

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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.



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