CVE-2026-43348

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> mshv_vtl: Fix vmemmap_shift exceeding MAX_FOLIO_ORDER<br /> <br /> When registering VTL0 memory via MSHV_ADD_VTL0_MEMORY, the kernel<br /> computes pgmap-&gt;vmemmap_shift as the number of trailing zeros in the<br /> OR of start_pfn and last_pfn, intending to use the largest compound<br /> page order both endpoints are aligned to.<br /> <br /> However, this value is not clamped to MAX_FOLIO_ORDER, so a<br /> sufficiently aligned range (e.g. physical range<br /> [0x800000000000, 0x800080000000), corresponding to start_pfn=0x800000000<br /> with 35 trailing zeros) can produce a shift larger than what<br /> memremap_pages() accepts, triggering a WARN and returning -EINVAL:<br /> <br /> WARNING: ... memremap_pages+0x512/0x650<br /> requested folio size unsupported<br /> <br /> The MAX_FOLIO_ORDER check was added by<br /> commit 646b67d57589 ("mm/memremap: reject unreasonable folio/compound<br /> page sizes in memremap_pages()").<br /> <br /> Fix this by clamping vmemmap_shift to MAX_FOLIO_ORDER so we always<br /> request the largest order the kernel supports, in those cases, rather<br /> than an out-of-range value.<br /> <br /> Also fix the error path to propagate the actual error code from<br /> devm_memremap_pages() instead of hard-coding -EFAULT, which was<br /> masking the real -EINVAL return.