{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-89742",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-89742"
  ],
  "published": "2026-09-11T19:47:07Z",
  "summary": "rapidio: mport_cdev: fix use-after-free in dma_req_free()",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nrapidio: mport_cdev: fix use-after-free in dma_req_free()\n\ndma_req_free() acquires buf_mutex through req->map, drops the mapping\nreference with kref_put(), and then dereferences req->map again to unlock\nthe mutex.\n\nIf kref_put() drops the last reference, mport_release_mapping() frees the\nmapping, and the subsequent mutex_unlock() dereferences a freed object. \nThis is a use-after-free.\n\nFix this by caching map and md before kref_put(), clearing req->map while\nholding buf_mutex, and using the cached md for mutex unlocking.\n\nThe bug is reachable from userspace via the RapidIO mport character device\ninterface.",
  "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": [
        "1:6.1.47-1+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": "6.1.188",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-89742"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/00c5ed913b0dc563fbeb8a97ea8916c03bbbbf6a"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/fc79c07cdcde02c5b17633d78777de6ac2c14b29"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/26ccfe7d69e27b0d933ae0a64a23a0cb9b9a85a6"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/bd8881c24a9520f9c3d3e855d866197f63e471a7"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/9a9929ec875ff20922c90c96fd544ae8a2a61a8d"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/e6e925cc1f8067c65c7bec3da50a0ead3b3ef4e0"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/211c68d817a3d9dc14c0026a59da7cac30f8147e"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/5cbef379a94b161726c5f504598bf4791d45cedc"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-09-14T12:06:03Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The use-after-free is reached only through local ioctls on /dev/rio_mportN (RIO_ALLOC_DMA, RIO_TRANSFER with a kernel DMA handle, RIO_FREE_DMA, then close or RIO_WAIT_FOR_ASYNC). RapidIO is a board-level fabric, and this dma_req_free() path is not driven by received packets.\nAC:L - An attacker who can open the mport node deterministically allocates a DMA mapping, submits an async RIO_TRANSFER that takes a kref on it, drops the owner ref with RIO_FREE_DMA, then frees the request so dma_req_free() performs the last kref_put(); no condition outside the attacker\u2019s control is required.\nPR:L - mport_cdev_open() and the DMA ioctls perform no capable() checks; access is gated only by /dev/rio_mportN permissions, and RapidIO deployments commonly give fabric-management daemons group access to that node, so an unprivileged local user with the device can drive the bug.\nUI:N - Exploitation is entirely self-driven via the attacker\u2019s own open/ioctl/close sequence on the mport character device; no separate victim action such as mounting a filesystem or opening a file is required.\nS:U - The freed rio_mport_mapping and the subsequent mutex unlock occur in kernel heap within the host OS authority; this is a standard kernel use-after-free and does not cross a VM, IOMMU, or sandbox boundary.\nC:H - dma_req_free() dereferences req->map after mport_release_mapping() has kfree\u2019d that kmalloc object; reclaiming the slab lets an attacker control map->md and read through the dangling pointer, a classic use-after-free disclosure primitive.\nI:H - Unlocking buf_mutex via a reclaimed map->md causes mutex_unlock() on an attacker-chosen address (fake-mutex wait_list write), so the use-after-free is exploitable for arbitrary kernel write and control-flow hijack.\nA:H - Use-after-free of rio_mport_mapping during mutex_unlock() oopses or panics under slab poisoning or init_on_free, and targeting a fake md leaves the real buf_mutex locked, deadlocking mapping paths and crashing or hanging the kernel."
    }
  }
}