CVE-2021-46935 (GCVE-0-2021-46935)

Vulnerability from cvelistv5 – Published: 2024-02-27 09:44 – Updated: 2026-05-11 13:44
VLAI
Title
binder: fix async_free_space accounting for empty parcels
Summary
In the Linux kernel, the following vulnerability has been resolved: binder: fix async_free_space accounting for empty parcels In 4.13, commit 74310e06be4d ("android: binder: Move buffer out of area shared with user space") fixed a kernel structure visibility issue. As part of that patch, sizeof(void *) was used as the buffer size for 0-length data payloads so the driver could detect abusive clients sending 0-length asynchronous transactions to a server by enforcing limits on async_free_size. Unfortunately, on the "free" side, the accounting of async_free_space did not add the sizeof(void *) back. The result was that up to 8-bytes of async_free_space were leaked on every async transaction of 8-bytes or less. These small transactions are uncommon, so this accounting issue has gone undetected for several years. The fix is to use "buffer_size" (the allocated buffer size) instead of "size" (the logical buffer size) when updating the async_free_space during the free operation. These are the same except for this corner case of asynchronous transactions with payloads < 8 bytes.
Severity
No CVSS data available.
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator (v2.0.3)
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 74310e06be4d74dcf67cd108366710dee5c576d5 , < 2d2df539d05205fd83c404d5f2dff48d36f9b495 (git)
Affected: 74310e06be4d74dcf67cd108366710dee5c576d5 , < 7c7064402609aeb6fb11be1b4ec10673ff17b593 (git)
Affected: 74310e06be4d74dcf67cd108366710dee5c576d5 , < 103b16a8c51f96d5fe063022869ea906c256e5da (git)
Affected: 74310e06be4d74dcf67cd108366710dee5c576d5 , < 1cb8444f3114f0bb2f6e3bcadcf09aa4a28425d4 (git)
Affected: 74310e06be4d74dcf67cd108366710dee5c576d5 , < 17691bada6b2f1d5f1c0f6d28cd9d0727023b0ff (git)
Affected: 74310e06be4d74dcf67cd108366710dee5c576d5 , < cfd0d84ba28c18b531648c9d4a35ecca89ad9901 (git)
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Linux Linux Affected: 4.14
Unaffected: 0 , < 4.14 (semver)
Unaffected: 4.14.261 , ≤ 4.14.* (semver)
Unaffected: 4.19.224 , ≤ 4.19.* (semver)
Unaffected: 5.4.170 , ≤ 5.4.* (semver)
Unaffected: 5.10.90 , ≤ 5.10.* (semver)
Unaffected: 5.15.13 , ≤ 5.15.* (semver)
Unaffected: 5.16 , ≤ * (original_commit_for_fix)
Create a notification for this product.
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2025-11-21T14:46:48+00:00",
      "cve": "CVE-2021-46935",
      "id": "CVE-2021-46935",
      "initial_release_date": "2021-01-01T00:00:00+00:00",
      "product_status:known_affected": "42",
      "product_status:known_not_affected": "156",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: binder: fix async_free_space accounting for empty parcels",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-46935.json",
      "version": "3"
    },
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      "dataType": "CVE_RECORD",
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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.


Detection rules are retrieved from Rulezet.