{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-80550",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-80550"
  ],
  "published": "2026-08-26T14:37:59Z",
  "summary": "s390/vfio_ccw: Fix out of bounds check on CCW array",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/vfio_ccw: Fix out of bounds check on CCW array\n\nThe routine ccwchain_calc_length() counts the number of channel\ncommand words (CCWs) that are chained together in a single channel\nprogram, and rejects anything larger than CCWCHAIN_LEN_MAX (256) CCWs.\n\nThe loop itself is \"do..while (count < 257)\", and while the logic in\nis_cpa_within_range() correctly adjusts between the 0-index array of\nCCWs and the count of CCWs starting at 1, this means it would look\nat a possible 257th CCW before ending the loop and (correctly)\nreturning an error.\n\nFix this by restructuring the loop to break as soon as 256 CCWs\n(thus indexes 0-255) are examined, without looking at memory\noutside the range.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:L"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.184",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-80550"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/0282fb1c4b638eecfe2cc558092c460911d8f7e2"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/907adc667d902fafbdb2d740d57b55bd025dc4cd"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/f20be33d093ce7630c17ff7ed93caf7eaf8ac1a3"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/af3f80ca4c8b17f20f9e588def076288fdb49e65"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/499a8a66b1598bfab97182aed15e0f1646074a3d"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/4c2e1d359d7a2b82cdf3254e4e480af9417f99fb"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/d5d096cd9369e986d4e5153baa86b8b35c283e09"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/a005b7f1a491ffda61bff0fd0f6548f8986fb977"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-27T05:18:36Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.9,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The bug is reached only via local VFIO-ccw mediated-device write() on the I/O region (guest channel program relayed by QEMU into fsm_io_request\u2192cp_init\u2192ccwchain_calc_length); vfio-ccw has no network, adjacent-radio, or physical-bus entry point.\nAC:L - An attacker fully controls guest channel program content and can reliably submit 256 command-chained CCWs so ccwchain_calc_length() reaches the 257th iteration; no race, special timing, or uncontrollable heap layout is required beyond crafting the CCW chain.\nPR:N - A malicious KVM guest with an assigned vfio-ccw mediated subchannel needs no host credentials or capabilities; it triggers the bug by issuing normal guest I/O that QEMU forwards through VFIO, without init-namespace root or admin setup privileges at exploit time.\nUI:N - Exploitation requires only the attacker's own channel program submission through VFIO passthrough I/O once the device is assigned; no separate victim mount, click, or other user action is needed.\nS:C - Guest-supplied channel programs are parsed in the host kernel cp_init() path during vfio-ccw device passthrough on IBM Z/LinuxONE, so the out-of-bounds read crosses the guest-to-host VFIO virtualization boundary and can compromise hypervisor memory outside the VM security scope.\nC:H - ccwchain_calc_length() reads one struct ccw1 (8 bytes) past the 256-element guest_cp kmalloc buffer when all CCWs are chained, constituting a kernel heap out-of-bounds read of adjacent slab memory that per kernel guidance enables information disclosure primitives.\nI:N - The vulnerability is a single out-of-bounds read used only for chain/TIC validation before returning -EINVAL; it performs no out-of-bounds write and does not modify host or guest data, channel program state, or kernel control structures on the error path.\nA:L - The out-of-bounds read typically does not crash production kernels because the access stays within the same kmalloc slab page, but KASAN-instrumented or hardened builds can detect it and fault; availability impact is limited rather than a reliable host panic."
    }
  }
}