{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2024-45020",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2024-45020"
  ],
  "published": "2024-09-11T15:14:19Z",
  "summary": "bpf: Fix a kernel verifier crash in stacksafe()",
  "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 &&\n        old->stack[spi].slot_type[i % BPF_REG_SIZE] !=\n        cur->stack[spi].slot_type[i % BPF_REG_SIZE])\n            return false;\n\nThe 'i' iterates old->allocated_stack.\nIf cur->allocated_stack < old->allocated_stack the out-of-bound\naccess will happen.\n\nTo fix the issue add 'i >= cur->allocated_stack' check such that if\nthe condition is true, stacksafe() should fail. Otherwise,\ncur->stack[spi].slot_type[i % BPF_REG_SIZE] memory access is legal.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.6.20-1+rpt1",
        "1:6.6.28-1+rpt1",
        "1:6.6.31-1+rpt1",
        "1:6.6.47-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
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            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
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            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
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            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v7l",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v8",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.28+rpt-rpi-2712",
            "binary_version": "1:6.6.28-1+rpt1"
          },
          {
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            "binary_version": "1:6.6.28-1+rpt1"
          },
          {
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            "binary_version": "1:6.6.28-1+rpt1"
          },
          {
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            "binary_version": "1:6.6.28-1+rpt1"
          },
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            "binary_version": "1:6.6.28-1+rpt1"
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            "binary_version": "1:6.6.31-1+rpt1"
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            "binary_version": "1:6.6.47-1+rpt1"
          },
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            "binary_version": "1:6.6.47-1+rpt1"
          },
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            "binary_version": "1:6.6.47-1+rpt1"
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      },
      "database_specific": {
        "per_version": {
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            "linux_commit": "6f16847710cc0502450788b9f12f0a14d3429668",
            "upstream_version": "6.6.20",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.6.48"
          },
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            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.6.48"
          }
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  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2024-45020"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7cad3174cc79519bf5f6c4441780264416822c08"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/6e3987ac310c74bb4dd6a2fa8e46702fe505fb2b"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/bed2eb964c70b780fb55925892a74f26cb590b25"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T11:52:36Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The vulnerability is reached through the bpf(BPF_PROG_LOAD) syscall, which requires local access to the system; there is no remote or adjacent-network path to the verifier.\nAC:L - The attacker fully authors the BPF program and deterministically constructs two converging paths with differing allocated_stack under an exact-comparison loop (as the upstream selftest demonstrates); no race or uncontrolled precondition is involved.\nPR:L - With unprivileged_bpf_disabled=0 an unprivileged local user can load SOCKET_FILTER/CGROUP_SKB programs, and BPF tokens (bpf_token_capable) delegate prog-load into unprivileged user namespaces; in both cases the verifier itself is the security boundary being broken.\nUI:N - The attacker triggers the bug entirely from their own process by loading a crafted BPF program; no action by any other user is required.\nS:U - The out-of-bounds access occurs in kernel memory within the same security authority as the attacking process; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - This is an out-of-bounds slab read reaching up to ~8KB past a small kmalloc'd bpf_stack_state array, far beyond a few bounded bytes, and the read bytes are compared against attacker-chosen slot_type values whose outcome is observable through verifier log/state-pruning behaviour, forming a heap-content oracle.\nI:H - Uncontrolled out-of-bounds heap data drives the state-equivalence verdict in exact-comparison mode, the mechanism that guarantees soundness of iterator and loop convergence; a wrongly-equal verdict prunes paths that were never verified, and an accepted unsafe program yields arbitrary kernel memory writes.\nA:H - When the compared frame has allocated_stack==0 the stack pointer is NULL/ZERO_SIZE_PTR, so the access is a deterministic kernel oops (the originally reported \"kernel verifier crash\"), and the slab case produces KASAN reports or faults on unmapped pages."
    }
  }
}