mm: swap: fix race between free_swap_and_cache() and swapoff()

MITRE NVD CVE.ORG JSON API Print: PDF PDF

Summary

CVECVE-2024-26960
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2024-05-01 06:15:12 UTC
Updated2026-05-12 12:16:28 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: mm: swap: fix race between free_swap_and_cache() and swapoff() There was previously a theoretical window where swapoff() could run and teardown a swap_info_struct while a call to free_swap_and_cache() was running in another thread. This could cause, amongst other bad possibilities, swap_page_trans_huge_swapped() (called by free_swap_and_cache()) to access the freed memory for swap_map. This is a theoretical problem and I haven't been able to provoke it from a test case. But there has been agreement based on code review that this is possible (see link below). Fix it by using get_swap_device()/put_swap_device(), which will stall swapoff(). There was an extra check in _swap_info_get() to confirm that the swap entry was not free. This isn't present in get_swap_device() because it doesn't make sense in general due to the race between getting the reference and swapoff. So I've added an equivalent check directly in free_swap_and_cache(). Details of how to provoke one possible issue (thanks to David Hildenbrand for deriving this): --8<----- __swap_entry_free() might be the last user and result in "count == SWAP_HAS_CACHE". swapoff->try_to_unuse() will stop as soon as soon as si->inuse_pages==0. So the question is: could someone reclaim the folio and turn si->inuse_pages==0, before we completed swap_page_trans_huge_swapped(). Imagine the following: 2 MiB folio in the swapcache. Only 2 subpages are still references by swap entries. Process 1 still references subpage 0 via swap entry. Process 2 still references subpage 1 via swap entry. Process 1 quits. Calls free_swap_and_cache(). -> count == SWAP_HAS_CACHE [then, preempted in the hypervisor etc.] Process 2 quits. Calls free_swap_and_cache(). -> count == SWAP_HAS_CACHE Process 2 goes ahead, passes swap_page_trans_huge_swapped(), and calls __try_to_reclaim_swap(). __try_to_reclaim_swap()->folio_free_swap()->delete_from_swap_cache()-> put_swap_folio()->free_swap_slot()->swapcache_free_entries()-> swap_entry_free()->swap_range_free()-> ... WRITE_ONCE(si->inuse_pages, si->inuse_pages - nr_entries); What stops swapoff to succeed after process 2 reclaimed the swap cache but before process1 finished its call to swap_page_trans_huge_swapped()? --8<-----

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from ADP

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-362 | CWE-362 CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED5.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary5.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 7c00bafee87c7bac7ed9eced7c161f8e5332cb4e d85c11c97ecf92d47a4b29e3faca714dc1f18d0d git Not specified
CNA Linux Linux affected 7c00bafee87c7bac7ed9eced7c161f8e5332cb4e 2da5568ee222ce0541bfe446a07998f92ed1643e git Not specified
CNA Linux Linux affected 7c00bafee87c7bac7ed9eced7c161f8e5332cb4e 1ede7f1d7eed1738d1b9333fd1e152ccb450b86a git Not specified
CNA Linux Linux affected 7c00bafee87c7bac7ed9eced7c161f8e5332cb4e 0f98f6d2fb5fad00f8299b84b85b6bc1b6d7d19a git Not specified
CNA Linux Linux affected 7c00bafee87c7bac7ed9eced7c161f8e5332cb4e 3ce4c4c653e4e478ecb15d3c88e690f12cbf6b39 git Not specified
CNA Linux Linux affected 7c00bafee87c7bac7ed9eced7c161f8e5332cb4e 363d17e7f7907c8e27a9e86968af0eaa2301787b git Not specified
CNA Linux Linux affected 7c00bafee87c7bac7ed9eced7c161f8e5332cb4e 82b1c07a0af603e3c47b906c8e991dc96f01688e git Not specified
CNA Linux Linux affected 4.11 Not specified
CNA Linux Linux unaffected 4.11 semver Not specified
CNA Linux Linux unaffected 5.10.215 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.154 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.84 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.24 6.6.* semver Not specified
CNA Linux Linux unaffected 6.7.12 6.7.* semver Not specified
CNA Linux Linux unaffected 6.8.3 6.8.* semver Not specified
CNA Linux Linux unaffected 6.9 * original_commit_for_fix Not specified
ADP Linux Linux Kernel affected 7c00bafee87c d85c11c97ecf custom Not specified
ADP Linux Linux Kernel affected 7c00bafee87c 2da5568ee222 custom Not specified
ADP Linux Linux Kernel affected 7c00bafee87c 1ede7f1d7eed custom Not specified
ADP Linux Linux Kernel affected 7c00bafee87c 0f98f6d2fb5f custom Not specified
ADP Linux Linux Kernel affected 7c00bafee87c 3ce4c4c653e4 custom Not specified
ADP Linux Linux Kernel affected 7c00bafee87c 363d17e7f790 custom Not specified
ADP Linux Linux Kernel affected 7c00bafee87c 82b1c07a0af6 custom Not specified
ADP Linux Linux Kernel unaffected 5.10.215 5.11 custom Not specified
ADP Linux Linux Kernel unaffected 6.1.84 6.2 custom Not specified
ADP Linux Linux Kernel unaffected 6.6.24 6.7 custom Not specified
ADP Linux Linux Kernel unaffected 6.8.3 6.9 custom Not specified
ADP Linux Linux Kernel unaffected 6.9 Not specified
ADP Linux Linux Kernel unaffected 4.11 custom Not specified
ADP Linux Linux Kernel affected 4.11 Not specified
ADP Linux Linux Kernel unaffected 5.15.154 5.16 custom Not specified
ADP Linux Linux Kernel unaffected 6.7.12 6.8 custom Not specified
ADP Siemens SIMATIC S7-1500 TM MFP - GNU/Linux Subsystem affected * custom Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/82b1c07a0af603e3c47b906c8e991dc96f01688e af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
lists.debian.org/debian-lts-announce/2024/06/msg00017.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org Mailing List, Third Party Advisory
git.kernel.org/stable/c/0f98f6d2fb5fad00f8299b84b85b6bc1b6d7d19a af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-265688.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/2da5568ee222ce0541bfe446a07998f92ed1643e af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/3ce4c4c653e4e478ecb15d3c88e690f12cbf6b39 af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/d85c11c97ecf92d47a4b29e3faca714dc1f18d0d af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/363d17e7f7907c8e27a9e86968af0eaa2301787b af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/1ede7f1d7eed1738d1b9333fd1e152ccb450b86a af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
© CVE.report 2026 |

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report