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GHSA-J2CC-C4FG-77CQ

Vulnerability from github – Published: 2024-10-21 18:30 – Updated: 2024-10-24 21:31

Details

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

mm/filemap: fix filemap_get_folios_contig THP panic

Patch series "memfd-pin huge page fixes".

Fix multiple bugs that occur when using memfd_pin_folios with hugetlb pages and THP. The hugetlb bugs only bite when the page is not yet faulted in when memfd_pin_folios is called. The THP bug bites when the starting offset passed to memfd_pin_folios is not huge page aligned. See the commit messages for details.

This patch (of 5):

memfd_pin_folios on memory backed by THP panics if the requested start offset is not huge page aligned:

BUG: kernel NULL pointer dereference, address: 0000000000000036 RIP: 0010:filemap_get_folios_contig+0xdf/0x290 RSP: 0018:ffffc9002092fbe8 EFLAGS: 00010202 RAX: 0000000000000002 RBX: 0000000000000002 RCX: 0000000000000002

The fault occurs here, because xas_load returns a folio with value 2:

filemap_get_folios_contig()
    for (folio = xas_load(&xas); folio && xas.xa_index <= end;
                    folio = xas_next(&xas)) {
            ...
            if (!folio_try_get(folio))   <-- BOOM

"2" is an xarray sibling entry. We get it because memfd_pin_folios does not round the indices passed to filemap_get_folios_contig to huge page boundaries for THP, so we load from the middle of a huge page range see a sibling. (It does round for hugetlbfs, at the is_file_hugepages test).

To fix, if the folio is a sibling, then return the next index as the starting point for the next call to filemap_get_folios_contig.

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-2024-49873"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-10-21T18:15:08Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/filemap: fix filemap_get_folios_contig THP panic\n\nPatch series \"memfd-pin huge page fixes\".\n\nFix multiple bugs that occur when using memfd_pin_folios with hugetlb\npages and THP.  The hugetlb bugs only bite when the page is not yet\nfaulted in when memfd_pin_folios is called.  The THP bug bites when the\nstarting offset passed to memfd_pin_folios is not huge page aligned.  See\nthe commit messages for details.\n\n\nThis patch (of 5):\n\nmemfd_pin_folios on memory backed by THP panics if the requested start\noffset is not huge page aligned:\n\nBUG: kernel NULL pointer dereference, address: 0000000000000036\nRIP: 0010:filemap_get_folios_contig+0xdf/0x290\nRSP: 0018:ffffc9002092fbe8 EFLAGS: 00010202\nRAX: 0000000000000002 RBX: 0000000000000002 RCX: 0000000000000002\n\nThe fault occurs here, because xas_load returns a folio with value 2:\n\n    filemap_get_folios_contig()\n        for (folio = xas_load(\u0026xas); folio \u0026\u0026 xas.xa_index \u003c= end;\n                        folio = xas_next(\u0026xas)) {\n                ...\n                if (!folio_try_get(folio))   \u003c-- BOOM\n\n\"2\" is an xarray sibling entry.  We get it because memfd_pin_folios does\nnot round the indices passed to filemap_get_folios_contig to huge page\nboundaries for THP, so we load from the middle of a huge page range see a\nsibling.  (It does round for hugetlbfs, at the is_file_hugepages test).\n\nTo fix, if the folio is a sibling, then return the next index as the\nstarting point for the next call to filemap_get_folios_contig.",
  "id": "GHSA-j2cc-c4fg-77cq",
  "modified": "2024-10-24T21:31:01Z",
  "published": "2024-10-21T18:30:56Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-49873"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/570dd14bfecf281fa467c80f8ec92b26370ee36a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c225c4f6056b46a8a5bf2ed35abf17a2d6887691"
    }
  ],
  "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-2024-49873 (GCVE-0-2024-49873)

Vulnerability from cvelistv5 – Published: 2024-10-21 18:01 – Updated: 2026-05-11 20:40

Title

mm/filemap: fix filemap_get_folios_contig THP panic

Summary

In the Linux kernel, the following vulnerability has been resolved: mm/filemap: fix filemap_get_folios_contig THP panic Patch series "memfd-pin huge page fixes". Fix multiple bugs that occur when using memfd_pin_folios with hugetlb pages and THP. The hugetlb bugs only bite when the page is not yet faulted in when memfd_pin_folios is called. The THP bug bites when the starting offset passed to memfd_pin_folios is not huge page aligned. See the commit messages for details. This patch (of 5): memfd_pin_folios on memory backed by THP panics if the requested start offset is not huge page aligned: BUG: kernel NULL pointer dereference, address: 0000000000000036 RIP: 0010:filemap_get_folios_contig+0xdf/0x290 RSP: 0018:ffffc9002092fbe8 EFLAGS: 00010202 RAX: 0000000000000002 RBX: 0000000000000002 RCX: 0000000000000002 The fault occurs here, because xas_load returns a folio with value 2: filemap_get_folios_contig() for (folio = xas_load(&xas); folio && xas.xa_index <= end; folio = xas_next(&xas)) { ... if (!folio_try_get(folio)) <-- BOOM "2" is an xarray sibling entry. We get it because memfd_pin_folios does not round the indices passed to filemap_get_folios_contig to huge page boundaries for THP, so we load from the middle of a huge page range see a sibling. (It does round for hugetlbfs, at the is_file_hugepages test). To fix, if the folio is a sibling, then return the next index as the starting point for the next call to filemap_get_folios_contig.

Severity

No CVSS data available.

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2024-10-22 13:46 UTC

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/570dd14bfecf281fa…
https://git.kernel.org/stable/c/c225c4f6056b46a8a…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 89c1905d9c140372b7f50ef48f42378cf85d9bc5 , < 570dd14bfecf281fa467c80f8ec92b26370ee36a (git) Affected: 89c1905d9c140372b7f50ef48f42378cf85d9bc5 , < c225c4f6056b46a8a5bf2ed35abf17a2d6887691 (git)
Linux	Linux	Affected: 6.11 Unaffected: 0 , < 6.11 (semver) Unaffected: 6.11.3 , ≤ 6.11.* (semver) Unaffected: 6.12 , ≤ * (original_commit_for_fix)

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JSON

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Sightings

Author	Source	Type	Date	Other

Nomenclature

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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.

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