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GHSA-F448-R8G9-P8J7

Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-21 15:31

Details

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

mm/migrate_device: clear stale mapping after freeing swapcache

__migrate_device_pages() reads the folio mapping before calling folio_free_swap(). When folio_free_swap() succeeds, the folio is removed from the swap cache, but the saved mapping still points to swap_space.

Passing the stale mapping to folio_migrate_mapping() makes it use the mapped-folio path for a folio that is no longer in swapcache. It can then operate on swap_space.i_pages with invalid reference accounting, eventually triggering a folio reference count BUG.

After a successful split, nr still contains the number of pages in the original large folio, although each resulting page is now a separate order-0 folio. Reset nr to 1 so each split folio is processed separately, including its own swapcache removal and mapping lookup.

Refresh the saved mapping after folio_free_swap() so the current folio state is used during migration.

Severity

7.8 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-89755"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-11T20:20:06Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/migrate_device: clear stale mapping after freeing swapcache\n\n__migrate_device_pages() reads the folio mapping before calling\nfolio_free_swap().  When folio_free_swap() succeeds, the folio is removed\nfrom the swap cache, but the saved mapping still points to swap_space.\n\nPassing the stale mapping to folio_migrate_mapping() makes it use the\nmapped-folio path for a folio that is no longer in swapcache.  It can then\noperate on swap_space.i_pages with invalid reference accounting,\neventually triggering a folio reference count BUG.\n\nAfter a successful split, nr still contains the number of pages in the\noriginal large folio, although each resulting page is now a separate\norder-0 folio.  Reset nr to 1 so each split folio is processed separately,\nincluding its own swapcache removal and mapping lookup.\n\nRefresh the saved mapping after folio_free_swap() so the current folio\nstate is used during migration.",
  "id": "GHSA-f448-r8g9-p8j7",
  "modified": "2026-09-21T15:31:37Z",
  "published": "2026-09-11T21:31:39Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89755"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/34a00895d032a414830d41106a09329ae6c251b6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4fa91f7bbc4135240b67daac03fc17d9e180a331"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8ffedc6573a665cdc31ebe47eae7b32b78d0df83"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-89755 (GCVE-0-2026-89755)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:46 – Updated: 2026-09-21 13:14

Title

mm/migrate_device: clear stale mapping after freeing swapcache

Summary

In the Linux kernel, the following vulnerability has been resolved: mm/migrate_device: clear stale mapping after freeing swapcache __migrate_device_pages() reads the folio mapping before calling folio_free_swap(). When folio_free_swap() succeeds, the folio is removed from the swap cache, but the saved mapping still points to swap_space. Passing the stale mapping to folio_migrate_mapping() makes it use the mapped-folio path for a folio that is no longer in swapcache. It can then operate on swap_space.i_pages with invalid reference accounting, eventually triggering a folio reference count BUG. After a successful split, nr still contains the number of pages in the original large folio, although each resulting page is now a separate order-0 folio. Reset nr to 1 so each split folio is processed separately, including its own swapcache removal and mapping lookup. Refresh the saved mapping after folio_free_swap() so the current folio state is used during migration.

Severity

7.8 (High)


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

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/4fa91f7bbc4135240…
https://git.kernel.org/stable/c/8ffedc6573a665cdc…
https://git.kernel.org/stable/c/34a00895d032a4148…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: df263d9a7dffee94ca5391120ee3b0587efa07f1 , < 4fa91f7bbc4135240b67daac03fc17d9e180a331 (git) Affected: df263d9a7dffee94ca5391120ee3b0587efa07f1 , < 8ffedc6573a665cdc31ebe47eae7b32b78d0df83 (git) Affected: df263d9a7dffee94ca5391120ee3b0587efa07f1 , < 34a00895d032a414830d41106a09329ae6c251b6 (git)
Linux	Linux	Affected: 6.6 Unaffected: 0 , < 6.6 (semver) Unaffected: 6.12.111 , ≤ 6.12.* (semver) Unaffected: 7.2.4 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "mm/migrate_device.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "4fa91f7bbc4135240b67daac03fc17d9e180a331",
              "status": "affected",
              "version": "df263d9a7dffee94ca5391120ee3b0587efa07f1",
              "versionType": "git"
            },
            {
              "lessThan": "8ffedc6573a665cdc31ebe47eae7b32b78d0df83",
              "status": "affected",
              "version": "df263d9a7dffee94ca5391120ee3b0587efa07f1",
              "versionType": "git"
            },
            {
              "lessThan": "34a00895d032a414830d41106a09329ae6c251b6",
              "status": "affected",
              "version": "df263d9a7dffee94ca5391120ee3b0587efa07f1",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "mm/migrate_device.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.6"
            },
            {
              "lessThan": "6.6",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.111",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/migrate_device: clear stale mapping after freeing swapcache\n\n__migrate_device_pages() reads the folio mapping before calling\nfolio_free_swap().  When folio_free_swap() succeeds, the folio is removed\nfrom the swap cache, but the saved mapping still points to swap_space.\n\nPassing the stale mapping to folio_migrate_mapping() makes it use the\nmapped-folio path for a folio that is no longer in swapcache.  It can then\noperate on swap_space.i_pages with invalid reference accounting,\neventually triggering a folio reference count BUG.\n\nAfter a successful split, nr still contains the number of pages in the\noriginal large folio, although each resulting page is now a separate\norder-0 folio.  Reset nr to 1 so each split folio is processed separately,\nincluding its own swapcache removal and mapping lookup.\n\nRefresh the saved mapping after folio_free_swap() so the current folio\nstate is used during migration."
        }
      ],
      "metrics": [
        {
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The bug is in __migrate_device_pages() on the migrate-to-device path (migrate_vma_pages), reached from local GPU HMM/SVM ioctls such as AMDKFD_IOC_SVM, DRM_NOUVEAU_SVM_BIND (DRM_RENDER_ALLOW), and Intel Xe drm_pagemap_migrate_to_devmem, not from network packets.\nAC:L - The attacker controls both preconditions: anonymous pages in their VMA, optionally kept in swapcache via pageout/swapin, then a migrate-to-VRAM ioctl. folio_free_swap() succeeds on locked mapped swapcache folios with swap count 0, which the attacker can arrange; no victim timing or uncontrollable layout is required.\nPR:L - Nouveau SVM bind is DRM_RENDER_ALLOW and KFD SVM/Xe pagemap paths have no capable() or DRM-master check. An unprivileged local user with typical render/video-group access to /dev/dri/renderD* or /dev/kfd on GPU systems can trigger the migration.\nUI:N - The attacker drives the whole sequence in their own process (anonymous mmap, optional madvise pageout, and GPU SVM migrate-to-device ioctls). No action by another user or administrator is required.\nS:U - Impact is host-kernel swap-cache and folio-refcount corruption, i.e. standard local privilege escalation in the same security authority, not a KVM/Xen guest-to-host escape or IOMMU/DMA boundary bypass.\nC:H - After folio_free_swap() the stale mapping still points at swap_space, so folio_migrate_mapping() xas_store()s a device-private folio into the global swap cache and underflows the source refcount; that UAF/type confusion of swap_space.i_pages yields an arbitrary kernel read primitive.\nI:H - The same xarray insertion and refcount underflow corrupt shared MM metadata (swap cache and folio references), which is exploitable for heap reuse and arbitrary kernel writes or control-flow hijack, not a bounded integrity change.\nA:H - Invalid reference accounting on swap_space.i_pages is documented to hit a folio reference-count BUG, and the resulting underflow/UAF also causes kernel oops or panic even without a completed exploit."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-21T13:14:58.853Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/34a00895d032a414830d41106a09329ae6c251b6"
        }
      ],
      "title": "mm/migrate_device: clear stale mapping after freeing swapcache",
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        "engine": "bippy-1.2.0"
      }
    }
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89755",
    "datePublished": "2026-09-11T19:46:58.295Z",
    "dateReserved": "2026-09-11T19:38:34.763Z",
    "dateUpdated": "2026-09-21T13:14:58.853Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

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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GHSA-F448-R8G9-P8J7

CVE-2026-89755 (GCVE-0-2026-89755)

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