ghsa-78xq-q56p-fpwx
Vulnerability from github
Published
2024-02-27 21:31
Modified
2024-02-27 21:31
Details

In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix masking negation logic upon negative dst register

The negation logic for the case where the off_reg is sitting in the dst register is not correct given then we cannot just invert the add to a sub or vice versa. As a fix, perform the final bitwise and-op unconditionally into AX from the off_reg, then move the pointer from the src to dst and finally use AX as the source for the original pointer arithmetic operation such that the inversion yields a correct result. The single non-AX mov in between is possible given constant blinding is retaining it as it's not an immediate based operation.

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{
  "affected": [],
  "aliases": [
    "CVE-2021-46974"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-02-27T19:04:07Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix masking negation logic upon negative dst register\n\nThe negation logic for the case where the off_reg is sitting in the\ndst register is not correct given then we cannot just invert the add\nto a sub or vice versa. As a fix, perform the final bitwise and-op\nunconditionally into AX from the off_reg, then move the pointer from\nthe src to dst and finally use AX as the source for the original\npointer arithmetic operation such that the inversion yields a correct\nresult. The single non-AX mov in between is possible given constant\nblinding is retaining it as it\u0027s not an immediate based operation.",
  "id": "GHSA-78xq-q56p-fpwx",
  "modified": "2024-02-27T21:31:27Z",
  "published": "2024-02-27T21:31:27Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-46974"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0e2dfdc74a7f4036127356d42ea59388f153f42c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2cfa537674cd1051a3b8111536d77d0558f33d5d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4d542ddb88fb2f39bf7f14caa2902f3e8d06f6ba"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/53e0db429b37a32b8fc706d0d90eb4583ad13848"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6eba92a4d4be8feb4dc33976abac544fa99d6ecc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7cf64d8679ca1cb20cf57d6a88bfee79a0922a66"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b9b34ddbe2076ade359cd5ce7537d5ed019e9807"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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