Vulnerability-Lookup

CVE-2026-64295 (GCVE-0-2026-64295)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:49 – Updated: 2026-07-25 08:49

Title

mm: page_ext: add count limit to page_ext_iter_next to prevent invalid PFN access

Summary

In the Linux kernel, the following vulnerability has been resolved: mm: page_ext: add count limit to page_ext_iter_next to prevent invalid PFN access The page_ext iteration API does not validate if the PFN still belongs to a valid section while advancing the iterator. When dynamically adding memory in the hotplug path, it can lead to a NULL pointer dereference during page_ext_lookup at the boundary of the last valid section when iterator count equals __pgcount. The for_each_page_ext() macro calls page_ext_iter_next() as its loop increment. for_each_page_ext() does a "__page_ext = page_ext_iter_next(&__iter)" at the end. This causes page_ext_iter_next() to increment iter->index past __pgcount and call page_ext_lookup(start_pfn + __pgcount). During memory hotplug (online), the PFN at start_pfn + __pgcount may belong to a section that has not yet been initialized, causing page_ext_lookup() to trigger a NULL pointer dereference. [ 14.555124][ T846] Call trace: [ 14.555125][ T846] lookup_page_ext+0x6c/0x108 (P) [ 14.555127][ T846] page_ext_lookup+0x30/0x3c [ 14.555129][ T846] __reset_page_owner+0x11c/0x260 [ 14.571201][ T846] __free_pages_ok+0x5e8/0x8e0 [ 14.571204][ T846] __free_pages_core+0x78/0xf0 [ 14.571206][ T846] generic_online_page+0x14/0x24 [ 14.597782][ T846] online_pages+0x178/0x30c [ 14.597784][ T846] memory_block_change_state+0x284/0x32c [ 14.597787][ T846] memory_subsys_online+0x4c/0x64 [ 14.597789][ T846] device_online+0x88/0xb0 [ 14.597791][ T846] online_memory_block+0x30/0x40 [ 14.597793][ T846] walk_memory_blocks+0xac/0xe8 [ 14.597794][ T846] add_memory_resource+0x280/0x298 [ 14.656161][ T846] add_memory+0x60/0x98 Move the iteration boundary enforcement inside the iterator functions, so callers cannot inadvertently access beyond the requested range.

Severity

No CVSS data available.

Assigner

Linux

References

3 references

URL	Tags
https://git.kernel.org/stable/c/8dcaa0f87a88d720d…
https://git.kernel.org/stable/c/377b1cd6bbcf32733…
https://git.kernel.org/stable/c/ffd017237cfe99e6e…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 9039b9096ea27a20f0349d1537537663c935c8ed , < 8dcaa0f87a88d720d13106f3a306c6b61d189d86 (git) Affected: 9039b9096ea27a20f0349d1537537663c935c8ed , < 377b1cd6bbcf327338cd951cc2fd74bc75540235 (git) Affected: 9039b9096ea27a20f0349d1537537663c935c8ed , < ffd017237cfe99e6e5602ab14179b0e6878a0840 (git)
Linux	Linux	Affected: 6.15 Unaffected: 0 , < 6.15 (semver) Unaffected: 6.18.39 , ≤ 6.18.* (semver) Unaffected: 7.1.4 , ≤ 7.1.* (semver) Unaffected: 7.2-rc3 , ≤ * (original_commit_for_fix)

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              "version": "7.1.4",
              "versionType": "semver"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: page_ext: add count limit to page_ext_iter_next to prevent invalid PFN access\n\nThe page_ext iteration API does not validate if the PFN still belongs to a\nvalid section while advancing the iterator.  When dynamically adding\nmemory in the hotplug path, it can lead to a NULL pointer dereference\nduring page_ext_lookup at the boundary of the last valid section when\niterator count equals __pgcount.\n\nThe for_each_page_ext() macro calls page_ext_iter_next() as its loop\nincrement.  for_each_page_ext() does a \"__page_ext =\npage_ext_iter_next(\u0026__iter)\" at the end.  This causes page_ext_iter_next()\nto increment iter-\u003eindex past __pgcount and call page_ext_lookup(start_pfn\n+ __pgcount).  During memory hotplug (online), the PFN at start_pfn +\n__pgcount may belong to a section that has not yet been initialized,\ncausing page_ext_lookup() to trigger a NULL pointer dereference.\n\n[   14.555124][  T846] Call trace:\n[   14.555125][  T846]  lookup_page_ext+0x6c/0x108 (P)\n[   14.555127][  T846]  page_ext_lookup+0x30/0x3c\n[   14.555129][  T846]  __reset_page_owner+0x11c/0x260\n[   14.571201][  T846]  __free_pages_ok+0x5e8/0x8e0\n[   14.571204][  T846]  __free_pages_core+0x78/0xf0\n[   14.571206][  T846]  generic_online_page+0x14/0x24\n[   14.597782][  T846]  online_pages+0x178/0x30c\n[   14.597784][  T846]  memory_block_change_state+0x284/0x32c\n[   14.597787][  T846]  memory_subsys_online+0x4c/0x64\n[   14.597789][  T846]  device_online+0x88/0xb0\n[   14.597791][  T846]  online_memory_block+0x30/0x40\n[   14.597793][  T846]  walk_memory_blocks+0xac/0xe8\n[   14.597794][  T846]  add_memory_resource+0x280/0x298\n[   14.656161][  T846]  add_memory+0x60/0x98\n\nMove the iteration boundary enforcement inside the iterator functions, so\ncallers cannot inadvertently access beyond the requested range."
        }
      ],
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        "dateUpdated": "2026-07-25T08:49:33.194Z",
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        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/8dcaa0f87a88d720d13106f3a306c6b61d189d86"
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          "url": "https://git.kernel.org/stable/c/377b1cd6bbcf327338cd951cc2fd74bc75540235"
        },
        {
          "url": "https://git.kernel.org/stable/c/ffd017237cfe99e6e5602ab14179b0e6878a0840"
        }
      ],
      "title": "mm: page_ext: add count limit to page_ext_iter_next to prevent invalid PFN access",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64295",
    "datePublished": "2026-07-25T08:49:33.194Z",
    "dateReserved": "2026-07-19T15:36:31.778Z",
    "dateUpdated": "2026-07-25T08:49:33.194Z",
    "state": "PUBLISHED"
  },
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    "suse_vex": {
      "aggregate_severity": "not set",
      "current_release_date": "2026-07-25T16:46:21Z",
      "cve": "CVE-2026-64295",
      "id": "CVE-2026-64295",
      "initial_release_date": "2026-07-25T16:46:21Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64295",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64295.json",
      "version": "2"
    }
  }
}

GHSA-V5HF-7896-CMM7

Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-25 12:31

Details

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

mm: page_ext: add count limit to page_ext_iter_next to prevent invalid PFN access

The page_ext iteration API does not validate if the PFN still belongs to a valid section while advancing the iterator. When dynamically adding memory in the hotplug path, it can lead to a NULL pointer dereference during page_ext_lookup at the boundary of the last valid section when iterator count equals __pgcount.

The for_each_page_ext() macro calls page_ext_iter_next() as its loop increment. for_each_page_ext() does a "__page_ext = page_ext_iter_next(&__iter)" at the end. This causes page_ext_iter_next() to increment iter->index past __pgcount and call page_ext_lookup(start_pfn + __pgcount). During memory hotplug (online), the PFN at start_pfn + __pgcount may belong to a section that has not yet been initialized, causing page_ext_lookup() to trigger a NULL pointer dereference.

[ 14.555124][ T846] Call trace: [ 14.555125][ T846] lookup_page_ext+0x6c/0x108 (P) [ 14.555127][ T846] page_ext_lookup+0x30/0x3c [ 14.555129][ T846] __reset_page_owner+0x11c/0x260 [ 14.571201][ T846] __free_pages_ok+0x5e8/0x8e0 [ 14.571204][ T846] __free_pages_core+0x78/0xf0 [ 14.571206][ T846] generic_online_page+0x14/0x24 [ 14.597782][ T846] online_pages+0x178/0x30c [ 14.597784][ T846] memory_block_change_state+0x284/0x32c [ 14.597787][ T846] memory_subsys_online+0x4c/0x64 [ 14.597789][ T846] device_online+0x88/0xb0 [ 14.597791][ T846] online_memory_block+0x30/0x40 [ 14.597793][ T846] walk_memory_blocks+0xac/0xe8 [ 14.597794][ T846] add_memory_resource+0x280/0x298 [ 14.656161][ T846] add_memory+0x60/0x98

Move the iteration boundary enforcement inside the iterator functions, so callers cannot inadvertently access beyond the requested range.

Show details on source website

JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-64295"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-25T10:17:10Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: page_ext: add count limit to page_ext_iter_next to prevent invalid PFN access\n\nThe page_ext iteration API does not validate if the PFN still belongs to a\nvalid section while advancing the iterator.  When dynamically adding\nmemory in the hotplug path, it can lead to a NULL pointer dereference\nduring page_ext_lookup at the boundary of the last valid section when\niterator count equals __pgcount.\n\nThe for_each_page_ext() macro calls page_ext_iter_next() as its loop\nincrement.  for_each_page_ext() does a \"__page_ext =\npage_ext_iter_next(\u0026__iter)\" at the end.  This causes page_ext_iter_next()\nto increment iter-\u003eindex past __pgcount and call page_ext_lookup(start_pfn\n+ __pgcount).  During memory hotplug (online), the PFN at start_pfn +\n__pgcount may belong to a section that has not yet been initialized,\ncausing page_ext_lookup() to trigger a NULL pointer dereference.\n\n[   14.555124][  T846] Call trace:\n[   14.555125][  T846]  lookup_page_ext+0x6c/0x108 (P)\n[   14.555127][  T846]  page_ext_lookup+0x30/0x3c\n[   14.555129][  T846]  __reset_page_owner+0x11c/0x260\n[   14.571201][  T846]  __free_pages_ok+0x5e8/0x8e0\n[   14.571204][  T846]  __free_pages_core+0x78/0xf0\n[   14.571206][  T846]  generic_online_page+0x14/0x24\n[   14.597782][  T846]  online_pages+0x178/0x30c\n[   14.597784][  T846]  memory_block_change_state+0x284/0x32c\n[   14.597787][  T846]  memory_subsys_online+0x4c/0x64\n[   14.597789][  T846]  device_online+0x88/0xb0\n[   14.597791][  T846]  online_memory_block+0x30/0x40\n[   14.597793][  T846]  walk_memory_blocks+0xac/0xe8\n[   14.597794][  T846]  add_memory_resource+0x280/0x298\n[   14.656161][  T846]  add_memory+0x60/0x98\n\nMove the iteration boundary enforcement inside the iterator functions, so\ncallers cannot inadvertently access beyond the requested range.",
  "id": "GHSA-v5hf-7896-cmm7",
  "modified": "2026-07-25T12:31:29Z",
  "published": "2026-07-25T12:31:29Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64295"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/377b1cd6bbcf327338cd951cc2fd74bc75540235"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8dcaa0f87a88d720d13106f3a306c6b61d189d86"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ffd017237cfe99e6e5602ab14179b0e6878a0840"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

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.

Action not permitted

CVE-2026-64295 (GCVE-0-2026-64295)

GHSA-V5HF-7896-CMM7

Tags

Sightings

Nomenclature