CVE-2026-93237 (GCVE-0-2026-93237)

Vulnerability from cvelistv5 – Published: 2026-09-24 15:33 – Updated: 2026-09-25 12:42
VLAI
Title
LoongArch: Add DIRECT_MAP_PHYSMEM_END definition
Summary
In the Linux kernel, the following vulnerability has been resolved: LoongArch: Add DIRECT_MAP_PHYSMEM_END definition get_free_mem_region() and mhp_get_pluggable_range() bound their search to DIRECT_MAP_PHYSMEM_END. LoongArch does not define it, so the fallback in include/linux/mm.h applies: under CONFIG_SPARSEMEM_VMEMMAP it is (1ULL << MAX_PHYSMEM_BITS) - 1, a compile-time constant that does not adapt to the CPU's physical address space bits (cpu_pabits, probed from CPUCFG1). The vmemmap window only covers physical space below 2^(cpu_pabits+1) (i.e. VMEMMAP_SIZE), so on CPUs with fewer physical address bits than MAX_PHYSMEM_BITS the fallback allows get_free_mem_region() to return a ZONE_DEVICE region outside the vmemmap window; vmemmap_populate() then wraps the memmap range around and maps it into low memory, silently corrupting the page tables. The same search also picked the top-of- address-space region that crashed memmap_init_zone_device() with amdkfd on Loongson-3C6000 in 6.16 [1]; the commit 2969b42c8f99 ("LoongArch/mm: align vmemmap to maximal folio size") keeps that region in bounds on current Loongson-3C6000 configs, but CPUs with smaller cpu_pabits (e.g. the Loongson-2K series) are still affected. Define DIRECT_MAP_PHYSMEM_END as the vmemmap-covered physical range, (1ULL << (cpu_pabits + 1)) - 1, capped at (1ULL << MAX_PHYSMEM_BITS) - 1 under CONFIG_SPARSEMEM, similar to the commit f3336b48cf9d ("riscv: mm: Define DIRECT_MAP_PHYSMEM_END"). [1] https://lore.kernel.org/amd-gfx/20250814032153.227285-1-jeffbai@aosc.io/
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 7b09f5af01ede480cbe7abcb281cf17550a46ff5 , < ab275a23b4d9f04ca6c2f5f6a3246194e045a761 (git)
Affected: 7b09f5af01ede480cbe7abcb281cf17550a46ff5 , < 55e18311c705cceef6c34d522ea387b1f0069bab (git)
Affected: 7b09f5af01ede480cbe7abcb281cf17550a46ff5 , < 2677f97a67fdbc62a82ce1faa67791f54451d36f (git)
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Linux Linux Affected: 6.2
Unaffected: 0 , < 6.2 (semver)
Unaffected: 6.18.51 , ≤ 6.18.* (semver)
Unaffected: 7.2.5 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/loongarch/include/asm/pgtable.h"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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              "version": "7b09f5af01ede480cbe7abcb281cf17550a46ff5",
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          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.2"
            },
            {
              "lessThan": "6.2",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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            {
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              "status": "unaffected",
              "version": "6.18.51",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.51",
                  "versionStartIncluding": "6.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.5",
                  "versionStartIncluding": "6.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "6.2",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nLoongArch: Add DIRECT_MAP_PHYSMEM_END definition\n\nget_free_mem_region() and mhp_get_pluggable_range() bound their search\nto DIRECT_MAP_PHYSMEM_END. LoongArch does not define it, so the fallback\nin include/linux/mm.h applies: under CONFIG_SPARSEMEM_VMEMMAP it is\n(1ULL \u003c\u003c MAX_PHYSMEM_BITS) - 1, a compile-time constant that does not\nadapt to the CPU\u0027s physical address space bits (cpu_pabits, probed from\nCPUCFG1).\n\nThe vmemmap window only covers physical space below 2^(cpu_pabits+1)\n(i.e. VMEMMAP_SIZE), so on CPUs with fewer physical address bits than\nMAX_PHYSMEM_BITS the fallback allows get_free_mem_region() to return\na ZONE_DEVICE region outside the vmemmap window; vmemmap_populate() then\nwraps the memmap range around and maps it into low memory, silently\ncorrupting the page tables. The same search also picked the top-of-\naddress-space region that crashed memmap_init_zone_device() with amdkfd\non Loongson-3C6000 in 6.16 [1]; the commit 2969b42c8f99 (\"LoongArch/mm:\nalign vmemmap to maximal folio size\") keeps that region in bounds on\ncurrent Loongson-3C6000 configs, but CPUs with smaller cpu_pabits (e.g.\nthe Loongson-2K series) are still affected.\n\nDefine DIRECT_MAP_PHYSMEM_END as the vmemmap-covered physical range,\n(1ULL \u003c\u003c (cpu_pabits + 1)) - 1, capped at (1ULL \u003c\u003c MAX_PHYSMEM_BITS) - 1\nunder CONFIG_SPARSEMEM, similar to the commit f3336b48cf9d (\"riscv: mm:\nDefine DIRECT_MAP_PHYSMEM_END\").\n\n[1] https://lore.kernel.org/amd-gfx/20250814032153.227285-1-jeffbai@aosc.io/"
        }
      ],
      "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 missing DIRECT_MAP_PHYSMEM_END is consumed by gfr_start() inside get_free_mem_region() when kgd2kfd_init_zone_device() calls devm_request_free_mem_region(\u0026iomem_resource) from amdgpu device init (HSA_AMD depends on LOONGARCH \u0026\u0026 64BIT); that is local PCI-probe HMM setup, not a remote protocol message.\nAC:L - With GFR_DESCENDING, gfr_start() always starts at min(iomem_resource.end, the mm.h fallback (1ULL\u003c\u003cMAX_PHYSMEM_BITS)-1) minus size, so on a CPU with cpu_pabits+1 below 48 the first ZONE_DEVICE slot is above VMEMMAP_SIZE and vmemmap_populate() wraps with no race or victim-owned device fault.\nPR:L - amdgpu PCI probe runs kgd2kfd_init_zone_device()\u2192devm_memremap_pages() with no capable() check from userspace; after that wrap the unprivileged local account on a typical ROCm/desktop LoongArch host (render group, /dev/kfd with kfd_open() likewise ungated) shares the corrupted init_mm without init-namespace root.\nUI:N - amdgpu_device init itself calls kgd2kfd_init_zone_device() and then pagemap_range()\u2192add_pages()\u2192vmemmap_populate() on PCI bind; no victim must mount media, open a file, or click, and any NOUVEAU_SVM_BIND the attacker issues is on their own DRM fd.\nS:U - LoongArch vmemmap_populate() (vmemmap_set_pmd/vmemmap_populate_hugepages) writes PTEs via pgd_offset_k() into init_mm for the wrapped pfn_to_page() VA, which is host kernel MM corruption, not a KVM guest-to-host escape or IOMMU/DMA bypass.\nC:H - __populate_section_memmap() sets start to (unsigned long)pfn_to_page() of the out-of-window ZONE_DEVICE PFN, so vmemmap_populate() maps struct-page backing over low kernel VAs; memmap_init_zone_device() then stores page-\u003epgmap and flags through that alias, disclosing kernel pointers and data those VAs previously mapped.\nI:H - vmemmap_set_pmd() installs PAGE_KERNEL PMDs at the wrapped address and memmap_init_zone_device() writes struct-page fields through pfn_to_page() into that alias, an unconstrained kernel page-table and metadata write rather than a bounded data tweak.\nA:H - The same top-of-address-space region already crashed memmap_init_zone_device() with amdkfd on Loongson-3C6000, and on smaller cpu_pabits the wrap leaves init_mm PTEs pointing at the wrong physical pages so later pfn_to_page() walks oops or panic the host."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-25T12:42:39.505Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/ab275a23b4d9f04ca6c2f5f6a3246194e045a761"
        },
        {
          "url": "https://git.kernel.org/stable/c/55e18311c705cceef6c34d522ea387b1f0069bab"
        },
        {
          "url": "https://git.kernel.org/stable/c/2677f97a67fdbc62a82ce1faa67791f54451d36f"
        }
      ],
      "title": "LoongArch: Add DIRECT_MAP_PHYSMEM_END definition",
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-93237",
    "datePublished": "2026-09-24T15:33:51.702Z",
    "dateReserved": "2026-09-17T16:02:15.095Z",
    "dateUpdated": "2026-09-25T12:42:39.505Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-93237",
      "date": "2026-09-28",
      "epss": "0.00173",
      "percentile": "0.06033"
    },
    "microsoft_vex": {
      "current_release_date": "2026-09-28T02:05:38.000Z",
      "cve": "CVE-2026-93237",
      "id": "msrc_CVE-2026-93237",
      "initial_release_date": "2026-09-28T02:05:38.000Z",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "LoongArch: Add DIRECT_MAP_PHYSMEM_END definition",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-93237.json",
      "version": "1"
    },
    "nvd": {
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        "affected": [
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              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "arch/loongarch/include/asm/pgtable.h"
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                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "status": "affected",
                    "version": "6.2"
                  },
                  {
                    "lessThan": "6.2",
                    "status": "unaffected",
                    "version": "0",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.18.*",
                    "status": "unaffected",
                    "version": "6.18.51",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "7.2.*",
                    "status": "unaffected",
                    "version": "7.2.5",
                    "versionType": "semver"
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                ]
              }
            ],
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nLoongArch: Add DIRECT_MAP_PHYSMEM_END definition\n\nget_free_mem_region() and mhp_get_pluggable_range() bound their search\nto DIRECT_MAP_PHYSMEM_END. LoongArch does not define it, so the fallback\nin include/linux/mm.h applies: under CONFIG_SPARSEMEM_VMEMMAP it is\n(1ULL \u003c\u003c MAX_PHYSMEM_BITS) - 1, a compile-time constant that does not\nadapt to the CPU\u0027s physical address space bits (cpu_pabits, probed from\nCPUCFG1).\n\nThe vmemmap window only covers physical space below 2^(cpu_pabits+1)\n(i.e. VMEMMAP_SIZE), so on CPUs with fewer physical address bits than\nMAX_PHYSMEM_BITS the fallback allows get_free_mem_region() to return\na ZONE_DEVICE region outside the vmemmap window; vmemmap_populate() then\nwraps the memmap range around and maps it into low memory, silently\ncorrupting the page tables. The same search also picked the top-of-\naddress-space region that crashed memmap_init_zone_device() with amdkfd\non Loongson-3C6000 in 6.16 [1]; the commit 2969b42c8f99 (\"LoongArch/mm:\nalign vmemmap to maximal folio size\") keeps that region in bounds on\ncurrent Loongson-3C6000 configs, but CPUs with smaller cpu_pabits (e.g.\nthe Loongson-2K series) are still affected.\n\nDefine DIRECT_MAP_PHYSMEM_END as the vmemmap-covered physical range,\n(1ULL \u003c\u003c (cpu_pabits + 1)) - 1, capped at (1ULL \u003c\u003c MAX_PHYSMEM_BITS) - 1\nunder CONFIG_SPARSEMEM, similar to the commit f3336b48cf9d (\"riscv: mm:\nDefine DIRECT_MAP_PHYSMEM_END\").\n\n[1] https://lore.kernel.org/amd-gfx/20250814032153.227285-1-jeffbai@aosc.io/"
          }
        ],
        "id": "CVE-2026-93237",
        "lastModified": "2026-09-25T13:17:17.880",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 1.8,
              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
            }
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        "published": "2026-09-24T16:17:19.447",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/2677f97a67fdbc62a82ce1faa67791f54451d36f"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/55e18311c705cceef6c34d522ea387b1f0069bab"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/ab275a23b4d9f04ca6c2f5f6a3246194e045a761"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-09-25T23:50:08Z",
      "cve": "CVE-2026-93237",
      "id": "CVE-2026-93237",
      "initial_release_date": "2026-09-25T23:50:08Z",
      "product_status:known_not_affected": "347",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-93237",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-93237.json",
      "version": "2"
    }
  }
}



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