CVE-2026-80686

In the Linux kernel, the following vulnerability has been resolved:

mm: migrate device: fix pte pfn/pte dirty called on non-present PTE

pte pfn() and pte dirty() have undefined behaviour when called on a non-present PTE. In migrate vma collect pmd(), these functions may be invoked on non-present entries (e.g., device-private entries), leading to potential crashes from pte pfn() or incorrect dirty folio accounting from pte dirty(). Fix both by guarding with pte present() checks.