CVE-2026-89754

/// Technical description

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

mm/pagewalk: fix stale walk->action escaping walk_pmd_range()

If ->pmd_entry() sets walk->action = ACTION_AGAIN, the pmd_none() check is

retried. The PMD entry may be cleared at the point of retry.

In this case, if walk->ops->install_pte is not specified, the code

continues to the next PMD entry in the range without resetting

walk->action to ACTION_SUBTREE.

This leaves walk->action erroneously set to ACTION_AGAIN, which is

incorrect.

This was incorrect but not problematic up until commit 3b89863c3fa4

("mm/pagewalk: fix race between concurrent split and refault") which

updated walk_pud_range() to check for walk->action == ACTION_AGAIN upon

walk_pmd_range()'s return, causing the PUD walk to be retried.

In this case this results in duplicate walk callbacks being invoked,

which is erroneous and will break any caller that is not idempotent

with respect to this (and waste time for those which are). The result

is an o

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References