CVE-2026-90383 (GCVE-0-2026-90383)
Vulnerability from cvelistv5
Published
2026-09-17 16:09
Modified
2026-10-21 12:51
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: misc: sgi-gru: remove interrupt-context page-table walks The GRU TLB miss handler walks a process's page tables without holding page-table locks or a reference to the mapped page. It also uses a kernel page-table accessor on user page tables and supports only PMD-level large mappings on x86-64. Remove the direct walker. Send interrupt faults directly to user polling mode so the existing call-OS fallback retries them in process context. Remove the mmap-lock failure statistic that can no longer be incremented.
References
Impacted products
Vendor Product Version
Linux Linux Version: 142586409c8be7dc071bb94d7cd2d69ccfd99b6b
Version: 142586409c8be7dc071bb94d7cd2d69ccfd99b6b
Version: 142586409c8be7dc071bb94d7cd2d69ccfd99b6b
Version: 142586409c8be7dc071bb94d7cd2d69ccfd99b6b
Version: 142586409c8be7dc071bb94d7cd2d69ccfd99b6b
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/misc/sgi-gru/grufault.c",
            "drivers/misc/sgi-gru/gruprocfs.c",
            "drivers/misc/sgi-gru/grutables.h"
          ],
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        {
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          "product": "Linux",
          "programFiles": [
            "drivers/misc/sgi-gru/grufault.c",
            "drivers/misc/sgi-gru/gruprocfs.c",
            "drivers/misc/sgi-gru/grutables.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.27"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "status": "unaffected",
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              "version": "6.12.110",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.160",
                  "versionStartIncluding": "2.6.27",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.110",
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                  "vulnerable": true
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                {
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              ],
              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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\u0027s 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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The attacker supplies the faulting VA by writing a virtual-mode GRU vload/vstore/bcopy into the mmap\u0027d 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-\u003ets_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."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:51:25.790Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/5a540ced720b4397306337cab34af1af4b30827c"
        },
        {
          "url": "https://git.kernel.org/stable/c/877423f595b60f8fe7c18b64a5d283d9e1732a13"
        },
        {
          "url": "https://git.kernel.org/stable/c/6248eb1833ff0adfdbbadd5f846c2f22e02a01b0"
        },
        {
          "url": "https://git.kernel.org/stable/c/ef81e4a1628ecfb9cfc442de10883f383faf17a1"
        },
        {
          "url": "https://git.kernel.org/stable/c/928a8e9f523df845fc496bcb9811013b67aabec5"
        }
      ],
      "title": "misc: sgi-gru: remove interrupt-context page-table walks",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90383",
    "datePublished": "2026-09-17T16:09:19.875Z",
    "dateReserved": "2026-09-11T19:38:34.809Z",
    "dateUpdated": "2026-10-21T12:51:25.790Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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