iommu/dma: Restore locking around msi_page_list

{
  "id": "8dcc6c6bd1dfc8e934da310c0cbf54cc78177c42ebc06cedadf1bc598a65a8b6",
  "url": "https://osv.dev/vulnerability/CVE-2026-90244",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "iommu/dma: Restore locking around msi_page_list",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: iommu/dma: Restore locking around msi_page_list Unlike a group's default domain, which is always freshly allocated and privately owned (iommu_group_alloc_default_domain()), VFIO type1's legacy container merges any newly attached group into an existing domain whenever their iommu_ops and cache-coherency enforcement match. iommu_dma_get_msi_page() only asserts the caller's own group mutex is held (iommu_group_mutex_assert()). On an IOMMU that publishes IOMMU_RESV_SW_MSI, e.g. ARM SMMU, a VM with two such devices assigned through the legacy container can have their guest drivers probe and allocate MSIs in parallel; each host-side VFIO_DEVICE_SET_IRQS lands on a different device fd and group mutex, but both devices' domains are the same merged domain, so both can enter iommu_dma_get_msi_page() concurrently and corrupt msi_page_list. commit 288683c92b1a (\"iommu: Make iommu_dma_prepare_msi() into a generic operation\") dropped the prior msi_prepare_lock on the reasoning that \"each iommu_domain is unique to a group,\" which holds for default domains but not this VFIO type1 case. Restore the static lock, since it's only guarding a corner case and will likely never be contended. iommufd avoids the equivalent problem by having its own callers (iommufd_sw_map_msi()) take a ctx-wide sw_msi_lock before ever reaching the shared list. VFIO type1 can't mirror that since it dispatches to iommu_dma_sw_msi() which is outside VFIO",
    "evidence": "osv:CVE-2026-90244",
    "products": [
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        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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            "value": "6.18.52",
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            "value": "7.2.6",
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    "severity": "high",
    "structured": {
      "id": "CVE-2026-90244",
      "aliases": [
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      "metrics": [
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      "modified": "2026-10-28T02:30:32.818930741Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/2af1e99ec14d226d66ceb9f16c663ee2568e6676",
        "https://git.kernel.org/stable/c/5a9e89ea34e0e34ac5d7e949042d665533549e40",
        "https://git.kernel.org/stable/c/e3c53e9173a47d5ce1fae020f2c6b1fb3c1123c2",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90244.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-90244",
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  "source_id": "core-osv",
  "document_id": 500093,
  "published_at": "2026-09-17T16:07:47.121+00:00"
}