{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-90383",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-90383"
  ],
  "published": "2026-09-17T16:10:40Z",
  "summary": "misc: sgi-gru: remove interrupt-context page-table walks",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmisc: sgi-gru: remove interrupt-context page-table walks\n\nThe GRU TLB miss handler walks a process's page tables without holding\npage-table locks or a reference to the mapped page. It also uses a kernel\npage-table accessor on user page tables and supports only PMD-level large\nmappings on x86-64.\n\nRemove the direct walker. Send interrupt faults directly to user polling\nmode so the existing call-OS fallback retries them in process context.\n\nRemove the mmap-lock failure statistic that can no longer be incremented.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "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-2026-90383"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/877423f595b60f8fe7c18b64a5d283d9e1732a13"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/6248eb1833ff0adfdbbadd5f846c2f22e02a01b0"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ef81e4a1628ecfb9cfc442de10883f383faf17a1"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/928a8e9f523df845fc496bcb9811013b67aabec5"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-09-18T17:55:42Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The attacker supplies the faulting VA by writing a virtual-mode GRU vload/vstore/bcopy into the mmap'd GSEG on /dev/gru. gru_fault loads the context; the miss is handled by gru_intr (default GRU_OPT_MISS_FMM_INTR) or ioctl GRU_USER_CALL_OS (gru_handle_user_call_os), both of which called atomic_pte_lookup on that missvaddr.\nAC:L - gru_create_new_context defaults to GRU_OPT_MISS_FMM_INTR, so a mapped-mode GRU instruction reliably hits gru_intr, which mmap_read_trylocks gts->ts_mm and runs atomic_pte_lookup. A 1GB hugetlb VMA is mis-walked with no race because pud_leaf is never checked; a second thread of the same process can also madvise/unmap during the unlocked walk.\nPR:L - gru_fops has no .open method and gru_file_mmap/gru_file_unlocked_ioctl do not call capable(). An unprivileged process that can open miscdevice \"gru\" (/dev/gru) can mmap the GSEG, ioctl GRU_CREATE_CONTEXT, and issue GRU instructions that reach atomic_pte_lookup; only gru_unload_all_contexts requires CAP_SYS_ADMIN.\nUI:N - The attacker alone opens /dev/gru, maps the GSEG, calls GRU_CREATE_CONTEXT, and issues the GRU instruction or GRU_USER_CALL_OS ioctl; no other user needs to act.\nS:U - atomic_pte_lookup feeds a GPA to tfh_write_restart on the host GRU chiplet. A bad PFN lets GRU DMA into host kernel or other-process memory, which is privilege escalation in the same kernel authority, not a guest-to-host or IOMMU-domain crossing.\nC:H - atomic_pte_lookup never tests pud_leaf, so pud_pgtable() on a 1GB hugetlb leaf treats attacker-controlled hugepage bytes as PMD/PTE entries. pte_pfn of that crafted entry is installed by tfh_write_restart, and gru_vload/bcopy then reads that physical page into the attacker-mapped GSEG. The walk also never pins the page, so a stale PFN can be read after reuse.\nI:H - gru_vstore, gru_bcopy, and AMO opcodes write through the GRU TLB entry programmed by tfh_write_restart. A PFN taken from the pud_leaf miswalk of attacker-controlled 1GB hugepage contents, or from an unpinned PTE reused after free, is therefore an arbitrary physical write.\nA:H - pte_offset_kernel() on a pud_leaf 1GB mapping (or on a PMD that is not a table) computes __va of a non-page-table PFN and dereferences it in gru_intr/atomic_pte_lookup, oopsing the kernel. GRU DMA through a stale unpinned PFN can also panic."
    }
  }
}