FKIE_CVE-2026-64186

Vulnerability from fkie_nvd - Published: 2026-07-19 16:18 - Updated: 2026-07-19 16:18
Severity
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().
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/488d2c76bd9f78433a70690d1054bfae3d39a407
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/62f9dfbf1aceae88b03c5ca08f7d36e943939dec
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8dfd3d8d74435344ee8dc9237596959c8b2a6cbe
Impacted products
Vendor Product Version
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{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/iommu/amd/debugfs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "488d2c76bd9f78433a70690d1054bfae3d39a407",
              "status": "affected",
              "version": "7a4ee419e8c144b747a8915856e91a034d7c8f34",
              "versionType": "git"
            },
            {
              "lessThan": "62f9dfbf1aceae88b03c5ca08f7d36e943939dec",
              "status": "affected",
              "version": "7a4ee419e8c144b747a8915856e91a034d7c8f34",
              "versionType": "git"
            },
            {
              "lessThan": "8dfd3d8d74435344ee8dc9237596959c8b2a6cbe",
              "status": "affected",
              "version": "7a4ee419e8c144b747a8915856e91a034d7c8f34",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/iommu/amd/debugfs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.17"
            },
            {
              "lessThan": "6.17",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.34",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommu/amd: Remove latent out-of-bounds access in IOMMU debugfs\n\nIn iommu_mmio_write() and iommu_capability_write(), the variables\ndbg_mmio_offset and dbg_cap_offset are declared as int. However, they\nare populated using kstrtou32_from_user(). If a user provides a\nsufficiently large value, it can become a negative integer.\n\nPrior to this patch, the AMD IOMMU debugfs implementation was already\nprotected by different mechanisms.\n\n1. #define OFS_IN_SZ 8 ensures the user string \u003c= 8 bytes, so\n   e.g. 0xffffffff isn\u0027t a valid input.\n\n  if (cnt \u003e OFS_IN_SZ)\n     return -EINVAL;\n\n2. Implicit type promotion in iommu_mmio_write(), dbg_mmio_offset is int\n   and iommu-\u003emmio_phys_end is u64\n\n  if (dbg_mmio_offset \u003e iommu-\u003emmio_phys_end - sizeof(u64))\n      return -EINVAL;\n\n3. The show handlers would currently catch the negative number and\n   refuse to perform the read.\n\nReplace kstrtou32_from_user() with kstrtos32_from_user() to parse the\ninput, and check for negative values to explicitly prevent out-of-bounds\nmemory accesses directly in iommu_mmio_write() and\niommu_capability_write()."
    }
  ],
  "id": "CVE-2026-64186",
  "lastModified": "2026-07-19T16:18:01.037",
  "metrics": {},
  "published": "2026-07-19T16:18:01.037",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/488d2c76bd9f78433a70690d1054bfae3d39a407"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/62f9dfbf1aceae88b03c5ca08f7d36e943939dec"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8dfd3d8d74435344ee8dc9237596959c8b2a6cbe"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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