ghsa-cj4f-m7fj-58gv
Vulnerability from github
Published
2024-02-27 12:31
Modified
2024-04-10 18:30
Details

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

parisc: Clear stale IIR value on instruction access rights trap

When a trap 7 (Instruction access rights) occurs, this means the CPU couldn't execute an instruction due to missing execute permissions on the memory region. In this case it seems the CPU didn't even fetched the instruction from memory and thus did not store it in the cr19 (IIR) register before calling the trap handler. So, the trap handler will find some random old stale value in cr19.

This patch simply overwrites the stale IIR value with a constant magic "bad food" value (0xbaadf00d), in the hope people don't start to try to understand the various random IIR values in trap 7 dumps.

Show details on source website


{
  "affected": [],
  "aliases": [
    "CVE-2021-46928"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-755"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-02-27T10:15:07Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nparisc: Clear stale IIR value on instruction access rights trap\n\nWhen a trap 7 (Instruction access rights) occurs, this means the CPU\ncouldn\u0027t execute an instruction due to missing execute permissions on\nthe memory region.  In this case it seems the CPU didn\u0027t even fetched\nthe instruction from memory and thus did not store it in the cr19 (IIR)\nregister before calling the trap handler. So, the trap handler will find\nsome random old stale value in cr19.\n\nThis patch simply overwrites the stale IIR value with a constant magic\n\"bad food\" value (0xbaadf00d), in the hope people don\u0027t start to try to\nunderstand the various random IIR values in trap 7 dumps.",
  "id": "GHSA-cj4f-m7fj-58gv",
  "modified": "2024-04-10T18:30:46Z",
  "published": "2024-02-27T12:31:10Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-46928"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/484730e5862f6b872dca13840bed40fd7c60fa26"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d01e9ce1af6116f812491d3d3873d204f10ae0b8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e96373f0a5f484bc1e193f9951dcb3adf24bf3f7"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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