CVE-2023-52935 Affecting kernel-rt-debug-modules-extra package, versions *


Severity

Recommended
high

Based on Red Hat Enterprise Linux security rating.

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  • Snyk IDSNYK-RHEL9-KERNELRTDEBUGMODULESEXTRA-9540381
  • published28 Mar 2025
  • disclosed27 Mar 2025

Introduced: 27 Mar 2025

NewCVE-2023-52935  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:9 kernel-rt-debug-modules-extra.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-debug-modules-extra package and not the kernel-rt-debug-modules-extra package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

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

mm/khugepaged: fix ->anon_vma race

If an ->anon_vma is attached to the VMA, collapse_and_free_pmd() requires it to be locked.

Page table traversal is allowed under any one of the mmap lock, the anon_vma lock (if the VMA is associated with an anon_vma), and the mapping lock (if the VMA is associated with a mapping); and so to be able to remove page tables, we must hold all three of them. retract_page_tables() bails out if an ->anon_vma is attached, but does this check before holding the mmap lock (as the comment above the check explains).

If we racily merged an existing ->anon_vma (shared with a child process) from a neighboring VMA, subsequent rmap traversals on pages belonging to the child will be able to see the page tables that we are concurrently removing while assuming that nothing else can access them.

Repeat the ->anon_vma check once we hold the mmap lock to ensure that there really is no concurrent page table access.

Hitting this bug causes a lockdep warning in collapse_and_free_pmd(), in the line "lockdep_assert_held_write(&vma->anon_vma->root->rwsem)". It can also lead to use-after-free access.

CVSS Base Scores

version 3.1