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

mm: fix crashes from deferred split racing folio migration

Even on 6.10-rc6, I've been seeing elusive "Bad page state"s (often on
flags when freeing, yet the flags shown are not bad: PG_locked had been
set and cleared??), and VM_BUG_ON_PAGE(page_ref_count(page) == 0)s from
deferred_split_scan()'s folio_put(), and a variety of other BUG and WARN
symptoms implying double free by deferred split and large folio migration.

6.7 commit 9bcef5973e31 ("mm: memcg: fix split queue list crash when large
folio migration") was right to fix the memcg-dependent locking broken in
85ce2c517ade ("memcontrol: only transfer the memcg data for migration"),
but missed a subtlety of deferred_split_scan(): it moves folios to its own
local list to work on them without split_queue_lock, during which time
folio->_deferred_list is not empty, but even the "right" lock does nothing
to secure the folio and the list it is on.

Fortunately, deferred_split_scan() is careful to use folio_try_get(): so
folio_migrate_mapping() can avoid the race by folio_undo_large_rmappable()
while the old folio's reference count is temporarily frozen to 0 - adding
such a freeze in the !mapping case too (originally, folio lock and
unmapping and no swap cache left an anon folio unreachable, so no freezing
was needed there: but the deferred split queue offers a way to reach it).
Published: 2024-08-07
Score: 5.5 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Ubuntu USN Ubuntu USN USN-7089-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7089-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7089-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7089-4 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7089-5 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7089-6 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7089-7 Linux kernel (Low Latency) vulnerabilities
Ubuntu USN Ubuntu USN USN-7090-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7095-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7156-1 Linux kernel (GKE) vulnerabilities
History

Wed, 11 Sep 2024 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 12 Aug 2024 10:30:00 +0000

Type Values Removed Values Added
Metrics threat_severity

Important

threat_severity

Moderate


Thu, 08 Aug 2024 21:30:00 +0000


Thu, 08 Aug 2024 15:15:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Weaknesses CWE-415
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
Metrics cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}


Wed, 07 Aug 2024 15:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: mm: fix crashes from deferred split racing folio migration Even on 6.10-rc6, I've been seeing elusive "Bad page state"s (often on flags when freeing, yet the flags shown are not bad: PG_locked had been set and cleared??), and VM_BUG_ON_PAGE(page_ref_count(page) == 0)s from deferred_split_scan()'s folio_put(), and a variety of other BUG and WARN symptoms implying double free by deferred split and large folio migration. 6.7 commit 9bcef5973e31 ("mm: memcg: fix split queue list crash when large folio migration") was right to fix the memcg-dependent locking broken in 85ce2c517ade ("memcontrol: only transfer the memcg data for migration"), but missed a subtlety of deferred_split_scan(): it moves folios to its own local list to work on them without split_queue_lock, during which time folio->_deferred_list is not empty, but even the "right" lock does nothing to secure the folio and the list it is on. Fortunately, deferred_split_scan() is careful to use folio_try_get(): so folio_migrate_mapping() can avoid the race by folio_undo_large_rmappable() while the old folio's reference count is temporarily frozen to 0 - adding such a freeze in the !mapping case too (originally, folio lock and unmapping and no swap cache left an anon folio unreachable, so no freezing was needed there: but the deferred split queue offers a way to reach it).
Title mm: fix crashes from deferred split racing folio migration
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-05-11T20:28:24.037Z

Reserved: 2024-07-30T07:40:12.252Z

Link: CVE-2024-42234

cve-icon Vulnrichment

Updated: 2024-09-11T12:42:24.305Z

cve-icon NVD

Status : Analyzed

Published: 2024-08-07T16:15:46.390

Modified: 2024-08-08T14:55:29.913

Link: CVE-2024-42234

cve-icon Redhat

Severity : Moderate

Publid Date: 2024-08-07T00:00:00Z

Links: CVE-2024-42234 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses