CVE-2026-80686: mm: migrate_device: fix pte_pfn/pte_dirty called on non-present PTE

CVE-2026-80686: mm: migrate_device: fix pte_pfn/pte_dirty called on non-present PTE

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

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.

The Linux kernel CVE team has assigned CVE-2026-80686 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.19 with commit 6c287605fd56466e645693eff3ae7c08fba56e0a and fixed in 6.1.184 with commit 26f9ca8ed42cba25d2c75daff13561cce6019395
	Issue introduced in 5.19 with commit 6c287605fd56466e645693eff3ae7c08fba56e0a and fixed in 6.6.153 with commit 5b948706f11a950bc73c5304630d0a7eafc40daf
	Issue introduced in 5.19 with commit 6c287605fd56466e645693eff3ae7c08fba56e0a and fixed in 6.12.103 with commit 86d55447de3738620b9a8272ff167ce97e7f7203
	Issue introduced in 5.19 with commit 6c287605fd56466e645693eff3ae7c08fba56e0a and fixed in 6.18.44 with commit 2be94d6b20789b8865b1864dae5fe458ca85e019
	Issue introduced in 5.19 with commit 6c287605fd56466e645693eff3ae7c08fba56e0a and fixed in 7.1.8 with commit 42f30fa5481a1f90571ccdfbb20d2e25e47ae76e
	Issue introduced in 5.19 with commit 6c287605fd56466e645693eff3ae7c08fba56e0a and fixed in 7.2 with commit 63867c82d0c0c2d182016a32b1cc0103116b0ea5

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-80686
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	mm/migrate_device.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/26f9ca8ed42cba25d2c75daff13561cce6019395
	https://git.kernel.org/stable/c/5b948706f11a950bc73c5304630d0a7eafc40daf
	https://git.kernel.org/stable/c/86d55447de3738620b9a8272ff167ce97e7f7203
	https://git.kernel.org/stable/c/2be94d6b20789b8865b1864dae5fe458ca85e019
	https://git.kernel.org/stable/c/42f30fa5481a1f90571ccdfbb20d2e25e47ae76e
	https://git.kernel.org/stable/c/63867c82d0c0c2d182016a32b1cc0103116b0ea5