ghsa-jf76-2c3p-rhc5
Vulnerability from github
Published
2024-09-11 18:31
Modified
2024-09-13 18:31
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Details

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

bpf: Fix a kernel verifier crash in stacksafe()

Daniel Hodges reported a kernel verifier crash when playing with sched-ext. Further investigation shows that the crash is due to invalid memory access in stacksafe(). More specifically, it is the following code:

if (exact != NOT_EXACT &&
    old->stack[spi].slot_type[i % BPF_REG_SIZE] !=
    cur->stack[spi].slot_type[i % BPF_REG_SIZE])
        return false;

The 'i' iterates old->allocated_stack. If cur->allocated_stack < old->allocated_stack the out-of-bound access will happen.

To fix the issue add 'i >= cur->allocated_stack' check such that if the condition is true, stacksafe() should fail. Otherwise, cur->stack[spi].slot_type[i % BPF_REG_SIZE] memory access is legal.

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{
  "affected": [],
  "aliases": [
    "CVE-2024-45020"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-787"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-09-11T16:15:07Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix a kernel verifier crash in stacksafe()\n\nDaniel Hodges reported a kernel verifier crash when playing with sched-ext.\nFurther investigation shows that the crash is due to invalid memory access\nin stacksafe(). More specifically, it is the following code:\n\n    if (exact != NOT_EXACT \u0026\u0026\n        old-\u003estack[spi].slot_type[i % BPF_REG_SIZE] !=\n        cur-\u003estack[spi].slot_type[i % BPF_REG_SIZE])\n            return false;\n\nThe \u0027i\u0027 iterates old-\u003eallocated_stack.\nIf cur-\u003eallocated_stack \u003c old-\u003eallocated_stack the out-of-bound\naccess will happen.\n\nTo fix the issue add \u0027i \u003e= cur-\u003eallocated_stack\u0027 check such that if\nthe condition is true, stacksafe() should fail. Otherwise,\ncur-\u003estack[spi].slot_type[i % BPF_REG_SIZE] memory access is legal.",
  "id": "GHSA-jf76-2c3p-rhc5",
  "modified": "2024-09-13T18:31:42Z",
  "published": "2024-09-11T18:31:06Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-45020"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6e3987ac310c74bb4dd6a2fa8e46702fe505fb2b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7cad3174cc79519bf5f6c4441780264416822c08"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bed2eb964c70b780fb55925892a74f26cb590b25"
    }
  ],
  "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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