CVE-2026-64186 (GCVE-0-2026-64186)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:41 – Updated: 2026-07-19 15:41
VLAI
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().
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 7a4ee419e8c144b747a8915856e91a034d7c8f34 , < 488d2c76bd9f78433a70690d1054bfae3d39a407 (git)
Affected: 7a4ee419e8c144b747a8915856e91a034d7c8f34 , < 62f9dfbf1aceae88b03c5ca08f7d36e943939dec (git)
Affected: 7a4ee419e8c144b747a8915856e91a034d7c8f34 , < 8dfd3d8d74435344ee8dc9237596959c8b2a6cbe (git)
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Linux Linux Affected: 6.17
Unaffected: 0 , < 6.17 (semver)
Unaffected: 6.18.34 , ≤ 6.18.* (semver)
Unaffected: 7.0.11 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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{
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      "affected": [
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          "product": "Linux",
          "programFiles": [
            "drivers/iommu/amd/debugfs.c"
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          "versions": [
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              "operator": "OR"
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      "descriptions": [
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          "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()."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-19T15:41:08.054Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/488d2c76bd9f78433a70690d1054bfae3d39a407"
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          "url": "https://git.kernel.org/stable/c/62f9dfbf1aceae88b03c5ca08f7d36e943939dec"
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        {
          "url": "https://git.kernel.org/stable/c/8dfd3d8d74435344ee8dc9237596959c8b2a6cbe"
        }
      ],
      "title": "iommu/amd: Remove latent out-of-bounds access in IOMMU debugfs",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64186",
    "datePublished": "2026-07-19T15:41:08.054Z",
    "dateReserved": "2026-07-19T07:54:57.039Z",
    "dateUpdated": "2026-07-19T15:41:08.054Z",
    "state": "PUBLISHED"
  },
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    "epss": {
      "cve": "CVE-2026-64186",
      "date": "2026-07-20",
      "epss": "0.00155",
      "percentile": "0.05063"
    },
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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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