iommu/amd: Remove latent out-of-bounds access in IOMMU debugfs

{
  "id": "8df4cd32269c7cba7857f1ddadd8c7b71285d460954a32ee284f5caf556200ea",
  "url": "https://osv.dev/vulnerability/CVE-2026-64186",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "iommu/amd: Remove latent out-of-bounds access in IOMMU debugfs",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: iommu/amd: Remove latent out-of-bounds access in IOMMU debugfs In iommu_mmio_write() and iommu_capability_write(), the variables dbg_mmio_offset and dbg_cap_offset are declared as int. However, they are populated using kstrtou32_from_user(). If a user provides a sufficiently large value, it can become a negative integer. Prior to this patch, the AMD IOMMU debugfs implementation was already protected by different mechanisms. 1. #define OFS_IN_SZ 8 ensures the user string <= 8 bytes, so e.g. 0xffffffff isn't a valid input. if (cnt > OFS_IN_SZ) return -EINVAL; 2. Implicit type promotion in iommu_mmio_write(), dbg_mmio_offset is int and iommu->mmio_phys_end is u64 if (dbg_mmio_offset > iommu->mmio_phys_end - sizeof(u64)) return -EINVAL; 3. The show handlers would currently catch the negative number and refuse to perform the read. Replace kstrtou32_from_user() with kstrtos32_from_user() to parse the input, and check for negative values to explicitly prevent out-of-bounds memory accesses directly in iommu_mmio_write() and iommu_capability_write().",
    "evidence": "osv:CVE-2026-64186",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.34",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.0.11",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-64186",
      "aliases": [
        "CVE-2026-64186"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "7a4ee419e8c144b747a8915856e91a034d7c8f34"
                },
                {
                  "fixed": "488d2c76bd9f78433a70690d1054bfae3d39a407"
                },
                {
                  "fixed": "62f9dfbf1aceae88b03c5ca08f7d36e943939dec"
                },
                {
                  "fixed": "8dfd3d8d74435344ee8dc9237596959c8b2a6cbe"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64186.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.17.0"
                },
                {
                  "fixed": "6.18.34"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.0.11"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64186.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:34.231135595Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/488d2c76bd9f78433a70690d1054bfae3d39a407",
        "https://git.kernel.org/stable/c/62f9dfbf1aceae88b03c5ca08f7d36e943939dec",
        "https://git.kernel.org/stable/c/8dfd3d8d74435344ee8dc9237596959c8b2a6cbe",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64186.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-64186",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64186.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-64186",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 501256,
  "published_at": "2026-07-19T15:41:08.054+00:00"
}