fkie_cve-2021-47221
Vulnerability from fkie_nvd
Published
2024-05-21 15:15
Modified
2025-04-29 19:07
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: mm/slub: actually fix freelist pointer vs redzoning It turns out that SLUB redzoning ("slub_debug=Z") checks from s->object_size rather than from s->inuse (which is normally bumped to make room for the freelist pointer), so a cache created with an object size less than 24 would have the freelist pointer written beyond s->object_size, causing the redzone to be corrupted by the freelist pointer. This was very visible with "slub_debug=ZF": BUG test (Tainted: G B ): Right Redzone overwritten ----------------------------------------------------------------------------- INFO: 0xffff957ead1c05de-0xffff957ead1c05df @offset=1502. First byte 0x1a instead of 0xbb INFO: Slab 0xffffef3950b47000 objects=170 used=170 fp=0x0000000000000000 flags=0x8000000000000200 INFO: Object 0xffff957ead1c05d8 @offset=1496 fp=0xffff957ead1c0620 Redzone (____ptrval____): bb bb bb bb bb bb bb bb ........ Object (____ptrval____): 00 00 00 00 00 f6 f4 a5 ........ Redzone (____ptrval____): 40 1d e8 1a aa @.... Padding (____ptrval____): 00 00 00 00 00 00 00 00 ........ Adjust the offset to stay within s->object_size. (Note that no caches of in this size range are known to exist in the kernel currently.)
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ce6e8bee7a3883e8008b30f5887dbb426aac6a35Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e41a49fadbc80b60b48d3c095d9e2ee7ef7c9a8ePatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f6ed2357541612a13a5841b3af4dc32ed984a25fPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/ce6e8bee7a3883e8008b30f5887dbb426aac6a35Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/e41a49fadbc80b60b48d3c095d9e2ee7ef7c9a8ePatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/f6ed2357541612a13a5841b3af4dc32ed984a25fPatch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel 5.13
linux linux_kernel 5.13
linux linux_kernel 5.13
linux linux_kernel 5.13
linux linux_kernel 5.13
linux linux_kernel 5.13


To clipboard 

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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/slub: actually fix freelist pointer vs redzoning\n\nIt turns out that SLUB redzoning (\"slub_debug=Z\") checks from\ns-\u003eobject_size rather than from s-\u003einuse (which is normally bumped to\nmake room for the freelist pointer), so a cache created with an object\nsize less than 24 would have the freelist pointer written beyond\ns-\u003eobject_size, causing the redzone to be corrupted by the freelist\npointer.  This was very visible with \"slub_debug=ZF\":\n\n  BUG test (Tainted: G    B            ): Right Redzone overwritten\n  -----------------------------------------------------------------------------\n\n  INFO: 0xffff957ead1c05de-0xffff957ead1c05df @offset=1502. First byte 0x1a instead of 0xbb\n  INFO: Slab 0xffffef3950b47000 objects=170 used=170 fp=0x0000000000000000 flags=0x8000000000000200\n  INFO: Object 0xffff957ead1c05d8 @offset=1496 fp=0xffff957ead1c0620\n\n  Redzone  (____ptrval____): bb bb bb bb bb bb bb bb               ........\n  Object   (____ptrval____): 00 00 00 00 00 f6 f4 a5               ........\n  Redzone  (____ptrval____): 40 1d e8 1a aa                        @....\n  Padding  (____ptrval____): 00 00 00 00 00 00 00 00               ........\n\nAdjust the offset to stay within s-\u003eobject_size.\n\n(Note that no caches of in this size range are known to exist in the\nkernel currently.)"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: mm/slub: en realidad corrige el puntero de lista libre frente a redzoning. Resulta que SLUB redzoning (\"slub_debug=Z\") verifica desde s-\u0026gt;object_size en lugar de s-\u0026gt;inuse (que normalmente se elimina para dejar espacio para el puntero de lista libre), por lo que un cach\u00e9 creado con un tama\u00f1o de objeto menor a 24 tendr\u00eda el puntero de lista libre escrito m\u00e1s all\u00e1 de s-\u0026gt;object_size, causando que el puntero de lista libre corrompa la zona roja. Esto fue muy visible con \"slub_debug=ZF\": prueba de BUG(contaminada: GB): zona roja derecha sobrescrita ---------------------------- ------------------------------------------------- INFORMACI\u00d3N : 0xffff957ead1c05de-0xffff957ead1c05df @offset=1502. Primer byte 0x1a en lugar de 0xbb INFORMACI\u00d3N: slab 0xffffef3950b47000 objetos=170 usados=170 fp=0x0000000000000000 banderas=0x80000000000000200 INFORMACI\u00d3N: Objeto 0xffff957ead1c05d8 @offset=1496 fp=0xffff9 57ead1c0620 Zona roja (____ptrval____): bb bb bb bb bb bb bb bb .... .... Objeto (____ptrval____): 00 00 00 00 00 f6 f4 a5 ........ Redzone (____ptrval____): 40 1d e8 1a aa @.... Relleno (____ptrval____): 00 00 00 00 00 00 00 00 ........ Ajuste el desplazamiento para permanecer dentro de s-\u0026gt;object_size. (Tenga en cuenta que actualmente no se sabe que existan cach\u00e9s de este rango de tama\u00f1o en el kernel)."
    }
  ],
  "id": "CVE-2021-47221",
  "lastModified": "2025-04-29T19:07:02.250",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2024-05-21T15:15:11.380",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/ce6e8bee7a3883e8008b30f5887dbb426aac6a35"
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-763"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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