{"cve":"CVE-2026-93237","nvd":{"published":"2026-09-24T16:17:19.447","modified":"2026-10-19T10:17:14.793","status":"Received","description":"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 << MAX_PHYSMEM_BITS) - 1, a compile-time constant that does not\nadapt to the CPU's 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 << (cpu_pabits + 1)) - 1, capped at (1ULL << 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/","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":[],"references":["https://git.kernel.org/stable/c/2677f97a67fdbc62a82ce1faa67791f54451d36f","https://git.kernel.org/stable/c/55e18311c705cceef6c34d522ea387b1f0069bab","https://git.kernel.org/stable/c/ab275a23b4d9f04ca6c2f5f6a3246194e045a761"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:56:02.509636177+00:00"},"epss":{"cve":"CVE-2026-93237","score":0.00173,"percentile":0.06743,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}