CVE-2026-43348
In the Linux kernel, the following vulnerability has been resolved:
mshv_vtl: Fix vmemmap_shift exceeding MAX_FOLIO_ORDER
When registering VTL0 memory via MSHV_ADD_VTL0_MEMORY, the kernel computes pgmap->vmemmap_shift as the number of trailing zeros in the OR of start_pfn and last_pfn, intending to use the largest compound page order both endpoints are aligned to.
However, this value is not clamped to MAX_FOLIO_ORDER, so a sufficiently aligned range (e.g. physical range [0x800000000000, 0x800080000000), corresponding to start_pfn=0x800000000 with 35 trailing zeros) can produce a shift larger than what memremap_pages() accepts, triggering a WARN and returning -EINVAL:
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The MAX_FOLIO_ORDER check was added by commit 646b67d57589 ("mm/memremap: reject unreasonable folio/compound page sizes in memremap_pages()").
Fix this by clamping vmemmap_shift to MAX_FOLIO_ORDER so we always request the largest order the kernel supports, in those cases, rather than an out-of-range value.
Also fix the error path to propagate the actual error code from devm_memremap_pages() instead of hard-coding -EFAULT, which was masking the real -EINVAL return.
Detalles técnicos trazas, registros y código del informe original
WARNING: ... memremap_pages+0x512/0x650 requested folio size unsupported
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 5.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.14%
- Percentil entre todas las CVEs puntuadas: 3
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
CWE
- NVD-CWE-noinfo
Referencias
JSON original (NVD)
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmshv_vtl: Fix vmemmap_shift exceeding MAX_FOLIO_ORDER\n\nWhen registering VTL0 memory via MSHV_ADD_VTL0_MEMORY, the kernel\ncomputes pgmap->vmemmap_shift as the number of trailing zeros in the\nOR of start_pfn and last_pfn, intending to use the largest compound\npage order both endpoints are aligned to.\n\nHowever, this value is not clamped to MAX_FOLIO_ORDER, so a\nsufficiently aligned range (e.g. physical range\n[0x800000000000, 0x800080000000), corresponding to start_pfn=0x800000000\nwith 35 trailing zeros) can produce a shift larger than what\nmemremap_pages() accepts, triggering a WARN and returning -EINVAL:\n\n WARNING: ... memremap_pages+0x512/0x650\n requested folio size unsupported\n\nThe MAX_FOLIO_ORDER check was added by\ncommit 646b67d57589 (\"mm/memremap: reject unreasonable folio/compound\npage sizes in memremap_pages()\").\n\nFix this by clamping vmemmap_shift to MAX_FOLIO_ORDER so we always\nrequest the largest order the kernel supports, in those cases, rather\nthan an out-of-range value.\n\nAlso fix the error path to propagate the actual error code from\ndevm_memremap_pages() instead of hard-coding -EFAULT, which was\nmasking the real -EINVAL return."
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