Linux hwe edge: In the Linux kernel, the following vulnerability has been resolved: riscv/mm: use physical alignment for vmemmap_start_pfn RISC-V computes… (CVE-2026-80682)

The vulnerability in the Linux kernel concerns the RISC-V architecture's calculation of vmemmap_start_pfn, which rounds phys_ram_base down to VMEMMAP_ADDR_ALIGN. A patch corrected a unit mismatch where MAX_FOLIO_VMEMMAP_ALIGN, measured in bytes of struct page storage, was incorrectly used as a physical address alignment. This caused alignment checks to fail on systems like QEMU virt where DRAM base is not aligned as expected, leading to kernel warnings during initialization. The fix converts MAX_FOLIO_VMEMMAP_ALIGN to the equivalent physical alignment before use, ensuring proper memory alignment and preventing the warning and potential instability.

The vulnerability can cause kernel warnings and instability on RISC-V systems due to improper memory alignment in the vmemmap area. It affects system stability and could impact confidentiality, integrity, and availability as indicated by the CVSS vector (C:H/I:H/A:H). No active exploitation has been reported.

A fix has been implemented in the Linux kernel to correct the alignment calculation for vmemmap_start_pfn on RISC-V architectures. Users should update to a kernel version that includes this patch. Since this is a kernel-level fix, applying the official kernel update is the recommended remediation. No additional mitigations are indicated.