dma-mapping: move dma_map_resource() sanity check into debug code

{
  "id": "9b781f7f60ff378f7ccbfed3b1f0a29ae75e8d67ea681d5993fb0adabc5f8a0d",
  "url": "https://osv.dev/vulnerability/CVE-2026-64149",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "dma-mapping: move dma_map_resource() sanity check into debug code",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: dma-mapping: move dma_map_resource() sanity check into debug code dma_map_resource() uses pfn_valid() to ensure the range is not RAM. However, pfn_valid() only checks for availability of the memory map for a PFN but it does not ensure that the PFN is actually backed by RAM. On ARM64 with SPARSEMEM (128MB section granularity), MMIO addresses that share a section with RAM will falsely trigger the WARN_ON_ONCE and cause dma_map_resource() to return DMA_MAPPING_ERROR. This causes a WARNING on Raspberry Pi 4 during spi_bcm2835 probe because the SPI FIFO register (0xfe204004) falls in the same sparsemem section as the end of RAM (0xf8000000-0xfbffffff), both in section 31 (0xf8000000-0xffffffff). Move the sanity check from dma_map_resource() into debug_dma_map_phys() and replace the unreliable pfn_valid() with pfn_valid() && !PageReserved(), which correctly identifies actual usable RAM without false positives for MMIO regions that happen to have struct pages. Since dma_map_resource() is dma_map_phys(DMA_ATTR_MMIO), the check applies equally to both APIs. Any non-reserved page represents kernel memory to a sufficient degree that using DMA_ATTR_MMIO on it is almost certainly wrong and risks breaking coherency on non-coherent platforms. ZONE_DEVICE pages used for PCI P2P DMA (MEMORY_DEVICE_PCI_P2PDMA) have PageReserved set, so they will not trigger a false positive. The check no longer blocks the mapping and uses err_",
    "evidence": "osv:CVE-2026-64149",
    "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-2026-64149",
      "aliases": [
        "CVE-2026-64149"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "f7326196a781622b33bfbdabb00f5e72b5fb5679"
                },
                {
                  "fixed": "181e67bc11c5ec5b87c6c512c2078752b23ca8d4"
                },
                {
                  "fixed": "004a777879ff629f6e0ca3d09ad09fa3452bcc4d"
                },
                {
                  "fixed": "af0c3f05866237f7592219bfe05387bc3bfc99b5"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64149.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.18.0"
                },
                {
                  "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-2026-64149.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.609578789Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/004a777879ff629f6e0ca3d09ad09fa3452bcc4d",
        "https://git.kernel.org/stable/c/181e67bc11c5ec5b87c6c512c2078752b23ca8d4",
        "https://git.kernel.org/stable/c/af0c3f05866237f7592219bfe05387bc3bfc99b5",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64149.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-64149",
        "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-2026-64149.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-64149",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 517750,
  "published_at": "2026-07-19T15:40:39.423+00:00"
}