{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2025-39961",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2025-39961"
  ],
  "published": "2025-10-09T12:15:19Z",
  "summary": "iommu/amd/pgtbl: Fix possible race while increase page table level",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\niommu/amd/pgtbl: Fix possible race while increase page table level\n\nThe AMD IOMMU host page table implementation supports dynamic page table levels\n(up to 6 levels), starting with a 3-level configuration that expands based on\nIOVA address. The kernel maintains a root pointer and current page table level\nto enable proper page table walks in alloc_pte()/fetch_pte() operations.\n\nThe IOMMU IOVA allocator initially starts with 32-bit address and onces its\nexhuasted it switches to 64-bit address (max address is determined based\non IOMMU and device DMA capability). To support larger IOVA, AMD IOMMU\ndriver increases page table level.\n\nBut in unmap path (iommu_v1_unmap_pages()), fetch_pte() reads\npgtable->[root/mode] without lock. So its possible that in exteme corner case,\nwhen increase_address_space() is updating pgtable->[root/mode], fetch_pte()\nreads wrong page table level (pgtable->mode). It does compare the value with\nlevel encoded in page table and returns NULL. This will result is\niommu_unmap ops to fail and upper layer may retry/log WARN_ON.\n\nCPU 0                                         CPU 1\n------                                       ------\nmap pages                                    unmap pages\nalloc_pte() -> increase_address_space()      iommu_v1_unmap_pages() -> fetch_pte()\n  pgtable->root = pte (new root value)\n                                             READ pgtable->[mode/root]\n\t\t\t\t\t       Reads new root, old mode\n  Updates mode (pgtable->mode += 1)\n\nSince Page table level updates are infrequent and already synchronized with a\nspinlock, implement seqcount to enable lock-free read operations on the read path.",
  "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": null,
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-39961"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/075abf0b1a958acfbea2435003d228e738e90346"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/cd92c8ab336c3a633d46e6f35ebcd3509ae7db3b"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7d462bdecb7d9c32934dab44aaeb7ea7d73a27a2"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/1e56310b40fd2e7e0b9493da9ff488af145bdd0c"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T12:19:11Z"
  }
}