fkie_cve-2021-46935
Vulnerability from fkie_nvd
Published
2024-02-27 10:15
Modified
2024-11-21 06:34
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/103b16a8c51f96d5fe063022869ea906c256e5daPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/17691bada6b2f1d5f1c0f6d28cd9d0727023b0ffPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1cb8444f3114f0bb2f6e3bcadcf09aa4a28425d4Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2d2df539d05205fd83c404d5f2dff48d36f9b495Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7c7064402609aeb6fb11be1b4ec10673ff17b593Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/cfd0d84ba28c18b531648c9d4a35ecca89ad9901Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/103b16a8c51f96d5fe063022869ea906c256e5daPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/17691bada6b2f1d5f1c0f6d28cd9d0727023b0ffPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/1cb8444f3114f0bb2f6e3bcadcf09aa4a28425d4Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/2d2df539d05205fd83c404d5f2dff48d36f9b495Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/7c7064402609aeb6fb11be1b4ec10673ff17b593Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/cfd0d84ba28c18b531648c9d4a35ecca89ad9901Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *


To clipboard 

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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbinder: fix async_free_space accounting for empty parcels\n\nIn 4.13, commit 74310e06be4d (\"android: binder: Move buffer out of area shared with user space\")\nfixed a kernel structure visibility issue. As part of that patch,\nsizeof(void *) was used as the buffer size for 0-length data payloads so\nthe driver could detect abusive clients sending 0-length asynchronous\ntransactions to a server by enforcing limits on async_free_size.\n\nUnfortunately, on the \"free\" side, the accounting of async_free_space\ndid not add the sizeof(void *) back. The result was that up to 8-bytes of\nasync_free_space were leaked on every async transaction of 8-bytes or\nless.  These small transactions are uncommon, so this accounting issue\nhas gone undetected for several years.\n\nThe fix is to use \"buffer_size\" (the allocated buffer size) instead of\n\"size\" (the logical buffer size) when updating the async_free_space\nduring the free operation. These are the same except for this\ncorner case of asynchronous transactions with payloads \u003c 8 bytes."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: binder: corrige la contabilidad async_free_space para paquetes vac\u00edos En 4.13, el commit 74310e06be4d (\"android: binder: mover el b\u00fafer fuera del \u00e1rea compartida con el espacio del usuario\") solucion\u00f3 un problema de visibilidad de la estructura del kernel. Como parte de ese parche, se us\u00f3 sizeof(void *) como tama\u00f1o de b\u00fafer para cargas de datos de longitud 0, de modo que el controlador pudiera detectar clientes abusivos que enviaran transacciones asincr\u00f3nicas de longitud 0 a un servidor imponiendo l\u00edmites en async_free_size. Desafortunadamente, en el lado \"libre\", la contabilidad de async_free_space no volvi\u00f3 a agregar el tama\u00f1o de (void *). El resultado fue que se filtraron hasta 8 bytes de async_free_space en cada transacci\u00f3n as\u00edncrona de 8 bytes o menos. Estas peque\u00f1as transacciones son poco comunes, por lo que este problema contable ha pasado desapercibido durante varios a\u00f1os. La soluci\u00f3n es utilizar \"buffer_size\" (el tama\u00f1o del b\u00fafer asignado) en lugar de \"size\" (el tama\u00f1o del b\u00fafer l\u00f3gico) al actualizar async_free_space durante la operaci\u00f3n libre. Son iguales excepto por este caso de esquina de transacciones asincr\u00f3nicas con payloads \u0026lt;8 bytes."
    }
  ],
  "id": "CVE-2021-46935",
  "lastModified": "2024-11-21T06:34:58.220",
  "metrics": {
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        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "NONE",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
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  "published": "2024-02-27T10:15:07.957",
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
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          "lang": "en",
          "value": "CWE-668"
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      "source": "nvd@nist.gov",
      "type": "Primary"
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}


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