Vulnerability-Lookup

GHSA-6P6F-GC59-4W3F

Vulnerability from github – Published: 2024-08-07 18:30 – Updated: 2024-08-08 15:31

Details

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).

Severity

5.5 (Medium)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2024-42234"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-415"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-08-07T16:15:46Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: fix crashes from deferred split racing folio migration\n\nEven on 6.10-rc6, I\u0027ve been seeing elusive \"Bad page state\"s (often on\nflags when freeing, yet the flags shown are not bad: PG_locked had been\nset and cleared??), and VM_BUG_ON_PAGE(page_ref_count(page) == 0)s from\ndeferred_split_scan()\u0027s folio_put(), and a variety of other BUG and WARN\nsymptoms implying double free by deferred split and large folio migration.\n\n6.7 commit 9bcef5973e31 (\"mm: memcg: fix split queue list crash when large\nfolio migration\") was right to fix the memcg-dependent locking broken in\n85ce2c517ade (\"memcontrol: only transfer the memcg data for migration\"),\nbut missed a subtlety of deferred_split_scan(): it moves folios to its own\nlocal list to work on them without split_queue_lock, during which time\nfolio-\u003e_deferred_list is not empty, but even the \"right\" lock does nothing\nto secure the folio and the list it is on.\n\nFortunately, deferred_split_scan() is careful to use folio_try_get(): so\nfolio_migrate_mapping() can avoid the race by folio_undo_large_rmappable()\nwhile the old folio\u0027s reference count is temporarily frozen to 0 - adding\nsuch a freeze in the !mapping case too (originally, folio lock and\nunmapping and no swap cache left an anon folio unreachable, so no freezing\nwas needed there: but the deferred split queue offers a way to reach it).",
  "id": "GHSA-6p6f-gc59-4w3f",
  "modified": "2024-08-08T15:31:28Z",
  "published": "2024-08-07T18:30:43Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-42234"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/be9581ea8c058d81154251cb0695987098996cad"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fc7facce686b64201dbf0b9614cc1d0bfad70010"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2024-42234 (GCVE-0-2024-42234)

Vulnerability from cvelistv5 – Published: 2024-08-07 15:14 – Updated: 2026-08-05 11:35

Title

mm: fix crashes from deferred split racing folio migration

Summary

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).

Severity

7.8 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2024-09-10 16:14 UTC

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/fc7facce686b64201…
https://git.kernel.org/stable/c/be9581ea8c058d811…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 9bcef5973e31020e5aa8571eb994d67b77318356 , < fc7facce686b64201dbf0b9614cc1d0bfad70010 (git) Affected: 9bcef5973e31020e5aa8571eb994d67b77318356 , < be9581ea8c058d81154251cb0695987098996cad (git)
Linux	Linux	Affected: 6.7 Unaffected: 0 , < 6.7 (semver) Unaffected: 6.9.10 , ≤ 6.9.* (semver) Unaffected: 6.10 , ≤ * (original_commit_for_fix)

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                "id": "CVE-2024-42234",
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: fix crashes from deferred split racing folio migration\n\nEven on 6.10-rc6, I\u0027ve been seeing elusive \"Bad page state\"s (often on\nflags when freeing, yet the flags shown are not bad: PG_locked had been\nset and cleared??), and VM_BUG_ON_PAGE(page_ref_count(page) == 0)s from\ndeferred_split_scan()\u0027s folio_put(), and a variety of other BUG and WARN\nsymptoms implying double free by deferred split and large folio migration.\n\n6.7 commit 9bcef5973e31 (\"mm: memcg: fix split queue list crash when large\nfolio migration\") was right to fix the memcg-dependent locking broken in\n85ce2c517ade (\"memcontrol: only transfer the memcg data for migration\"),\nbut missed a subtlety of deferred_split_scan(): it moves folios to its own\nlocal list to work on them without split_queue_lock, during which time\nfolio-\u003e_deferred_list is not empty, but even the \"right\" lock does nothing\nto secure the folio and the list it is on.\n\nFortunately, deferred_split_scan() is careful to use folio_try_get(): so\nfolio_migrate_mapping() can avoid the race by folio_undo_large_rmappable()\nwhile the old folio\u0027s reference count is temporarily frozen to 0 - adding\nsuch a freeze in the !mapping case too (originally, folio lock and\nunmapping and no swap cache left an anon folio unreachable, so no freezing\nwas needed there: but the deferred split queue offers a way to reach it)."
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            "version": "3.1"
          },
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              "value": "AV:L - The vulnerability is in core mm (THP deferred split queue vs. folio migration) and is reached entirely through local syscalls \u2014 mmap/madvise(MADV_HUGEPAGE)/munmap to queue folios, memory pressure to invoke the shrinker, and move_pages/mbind or direct compaction to migrate them. No network or physical access is involved.\nAC:L - The attacker controls both sides of the race and can create it deliberately: one thread loops partial-unmapping large anon folios onto the deferred split queue while others generate reclaim pressure and issue move_pages()/fault THPs to drive migration of those same folios. Retrying is free and unlimited, and no attacker-independent condition is required \u2014 the race was hit even accidentally under ordinary load.\nPR:L - Only an ordinary unprivileged local user is needed; move_pages() on the caller\u0027s own process requires just ptrace_may_access() on self and MPOL_MF_MOVE, not CAP_SYS_NICE, and THP allocation, partial unmap, and memory pressure need no capabilities at all.\nUI:N - The attacking process performs all steps itself with no victim action required; the shrinker and compaction/migration paths run autonomously in kernel context.\nS:U - The corruption is of kernel page/folio state within the same security authority as the exploited kernel; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The double free / refcount underflow returns a page to the buddy allocator while it is still mapped into the attacker\u0027s address space, allowing that page to be reallocated as a kernel slab page, page table, or kernel stack and read directly from userspace, giving arbitrary kernel memory disclosure.\nI:H - The same cross-allocation aliasing gives an arbitrary kernel write primitive \u2014 the attacker retains a writable userspace mapping of a page the kernel has re-handed to internal structures \u2014 plus the list corruption itself writes attacker-influenced pointers into the global split queue, making control-flow hijack and privilege escalation feasible.\nA:H - The reported symptoms are outright kernel crashes \u2014 \"Bad page state\", VM_BUG_ON_PAGE(page_ref_count(page) == 0), list_del corruption BUGs and assorted WARNs from double free \u2014 any of which panics or destabilizes the system, and the condition can be triggered repeatedly."
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    "datePublished": "2024-08-07T15:14:24.467Z",
    "dateReserved": "2024-07-30T07:40:12.252Z",
    "dateUpdated": "2026-08-05T11:35:59.332Z",
    "state": "PUBLISHED"
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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