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iommu/amd/pgtbl: Fix possible race while increase page table level

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: iommu/amd/pgtbl: Fix possible race while increase page table level The AMD IOMMU host page table implementation supports dynamic page table levels (up to 6 levels), starting with a 3-level configuration that expands based on IOVA address. The kernel maintains a root pointer and current page table level to enable proper page table walks in alloc_pte()/fetch_pte() operations. The IOMMU IOVA allocator initially starts with 32-bit address and onces its exhuasted it switches to 64-bit address (max address is determined based on IOMMU and device DMA capability). To support larger IOVA, AMD IOMMU driver increases page table level. But in unmap path (iommu_v1_unmap_pages()), fetch_pte() reads pgtable->[root/mode] without lock. So its possible that in exteme corner case, when increase_address_space() is updating pgtable->[root/mode], fetch_pte() reads wrong page table level (pgtable->mode). It does compare the value with level encoded in page table and returns NULL. This will result is iommu_unmap ops to fail and upper layer may retry/log WARN_ON. CPU 0 CPU 1 ------ ------ map pages unmap pages alloc_pte() -> increase_address_space() iommu_v1_unmap_pages() -> fetch_pte() pgtable->root = pte (new root value) READ pgtable->[mode/root] Reads new root, old mode Updates mode (pgtable->mode += 1) Since Page table level updates are infrequent and already synchronized with a spinlock, implement seqcount to enable lock-free re

Announced Source revision 1
Original source ↗

CVE-2025-39961

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2025-39961

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
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Prerequisites
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Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "754265bcab78a9014f0f99cd35e0d610fcd7dfa7",
        "lessThan": "075abf0b1a958acfbea2435003d228e738e90346",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "754265bcab78a9014f0f99cd35e0d610fcd7dfa7",
        "lessThan": "cd92c8ab336c3a633d46e6f35ebcd3509ae7db3b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "754265bcab78a9014f0f99cd35e0d610fcd7dfa7",
        "lessThan": "7d462bdecb7d9c32934dab44aaeb7ea7d73a27a2",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "754265bcab78a9014f0f99cd35e0d610fcd7dfa7",
        "lessThan": "1e56310b40fd2e7e0b9493da9ff488af145bdd0c",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6fb92f18555a7b8e085267d513612dc0ff9a5360",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "b15bf74405faa1a65025eb8a6eb337e140e5250a",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "0d50f7b1e8c80a8c20db5049e269468c059b0378",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "785ca708a908b9c596ede852470ba28b8dc3e40b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4.9.194",
        "lessThan": "4.10",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "4.14.146",
        "lessThan": "4.15",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "4.19.75",
        "lessThan": "4.20",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "5.2.17",
        "lessThan": "5.3",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "drivers/iommu/amd/amd_iommu_types.h",
      "drivers/iommu/amd/io_pgtable.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.3"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.3",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.108",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.49",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.16.9",
        "versionType": "semver",
        "lessThanOrEqual": "6.16.*"
      },
      {
        "status": "unaffected",
        "version": "6.17",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "drivers/iommu/amd/amd_iommu_types.h",
      "drivers/iommu/amd/io_pgtable.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2025-39961

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#30645 · Revision 1
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