LoongArch: Add DIRECT_MAP_PHYSMEM_END definition

{
  "id": "c01ac39f8cf0233c04dbdbdb00b9db99ae523e204500998e51382c755632c3ea",
  "url": "https://osv.dev/vulnerability/CVE-2026-93237",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "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.or",
    "evidence": "osv:CVE-2026-93237",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.51",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.5",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-93237",
      "aliases": [
        "CVE-2026-93237"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "introduced": "7b09f5af01ede480cbe7abcb281cf17550a46ff5"
                },
                {
                  "fixed": "ab275a23b4d9f04ca6c2f5f6a3246194e045a761"
                },
                {
                  "fixed": "55e18311c705cceef6c34d522ea387b1f0069bab"
                },
                {
                  "fixed": "2677f97a67fdbc62a82ce1faa67791f54451d36f"
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-93237.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.18.51"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.2.5"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-93237.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:34.007513865Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/2677f97a67fdbc62a82ce1faa67791f54451d36f",
        "https://git.kernel.org/stable/c/55e18311c705cceef6c34d522ea387b1f0069bab",
        "https://git.kernel.org/stable/c/ab275a23b4d9f04ca6c2f5f6a3246194e045a761",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93237.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-93237",
        "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/2026/93xxx/CVE-2026-93237.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-93237",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 501186,
  "published_at": "2026-09-24T15:33:51.702+00:00"
}