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GHSA-HC84-56CX-WR29

Vulnerability from github – Published: 2025-03-12 12:30 – Updated: 2025-03-13 18:32

Details

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

bpf: Fix softlockup in arena_map_free on 64k page kernel

On an aarch64 kernel with CONFIG_PAGE_SIZE_64KB=y, arena_htab tests cause a segmentation fault and soft lockup. The same failure is not observed with 4k pages on aarch64.

It turns out arena_map_free() is calling apply_to_existing_page_range() with the address returned by bpf_arena_get_kern_vm_start(). If this address is not page-aligned the code ends up calling apply_to_pte_range() with that unaligned address causing soft lockup.

Fix it by round up GUARD_SZ to PAGE_SIZE << 1 so that the division by 2 in bpf_arena_get_kern_vm_start() returns a page-aligned value.

Severity

3.3 (Low)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2025-21851"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-667"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-03-12T10:15:17Z",
    "severity": "LOW"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix softlockup in arena_map_free on 64k page kernel\n\nOn an aarch64 kernel with CONFIG_PAGE_SIZE_64KB=y,\narena_htab tests cause a segmentation fault and soft lockup.\nThe same failure is not observed with 4k pages on aarch64.\n\nIt turns out arena_map_free() is calling\napply_to_existing_page_range() with the address returned by\nbpf_arena_get_kern_vm_start().  If this address is not page-aligned\nthe code ends up calling apply_to_pte_range() with that unaligned\naddress causing soft lockup.\n\nFix it by round up GUARD_SZ to PAGE_SIZE \u003c\u003c 1 so that the\ndivision by 2 in bpf_arena_get_kern_vm_start() returns\na page-aligned value.",
  "id": "GHSA-hc84-56cx-wr29",
  "modified": "2025-03-13T18:32:21Z",
  "published": "2025-03-12T12:30:58Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-21851"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/517e8a7835e8cfb398a0aeb0133de50e31cae32b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/787d556a3de447e70964a4bdeba9196f62a62b1e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c1f3f3892d4526f18aaeffdb6068ce861e793ee3"
    }
  ],
  "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:L",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2025-21851 (GCVE-0-2025-21851)

Vulnerability from cvelistv5 – Published: 2025-03-12 09:42 – Updated: 2026-08-05 11:54

Title

bpf: Fix softlockup in arena_map_free on 64k page kernel

Summary

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix softlockup in arena_map_free on 64k page kernel On an aarch64 kernel with CONFIG_PAGE_SIZE_64KB=y, arena_htab tests cause a segmentation fault and soft lockup. The same failure is not observed with 4k pages on aarch64. It turns out arena_map_free() is calling apply_to_existing_page_range() with the address returned by bpf_arena_get_kern_vm_start(). If this address is not page-aligned the code ends up calling apply_to_pte_range() with that unaligned address causing soft lockup. Fix it by round up GUARD_SZ to PAGE_SIZE << 1 so that the division by 2 in bpf_arena_get_kern_vm_start() returns a page-aligned value.

Severity

7.8 (High)


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

3.3 (Low)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2025-10-01 19:26 UTC

CWE

CWE-667 - Improper Locking

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/c1f3f3892d4526f18…
https://git.kernel.org/stable/c/787d556a3de447e70…
https://git.kernel.org/stable/c/517e8a7835e8cfb39…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 317460317a02a1af512697e6e964298dedd8a163 , < c1f3f3892d4526f18aaeffdb6068ce861e793ee3 (git) Affected: 317460317a02a1af512697e6e964298dedd8a163 , < 787d556a3de447e70964a4bdeba9196f62a62b1e (git) Affected: 317460317a02a1af512697e6e964298dedd8a163 , < 517e8a7835e8cfb398a0aeb0133de50e31cae32b (git)
Linux	Linux	Affected: 6.9 Unaffected: 0 , < 6.9 (semver) Unaffected: 6.12.17 , ≤ 6.12.* (semver) Unaffected: 6.13.5 , ≤ 6.13.* (semver) Unaffected: 6.14 , ≤ * (original_commit_for_fix)

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              "attackComplexity": "LOW",
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              "baseScore": 3.3,
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              "confidentialityImpact": "NONE",
              "integrityImpact": "NONE",
              "privilegesRequired": "LOW",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L",
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              "value": "AV:L - The vulnerability is reached through the bpf(2) syscall \u2014 creating a BPF_MAP_TYPE_ARENA map, mmap()ing it, faulting in a page, and closing the fd. No network exposure is involved.\nAC:L - On an affected kernel (arm64 with 64K pages, a mainstream aarch64 distro/server configuration), the unaligned base address makes the non-terminating apply_to_pte_range() loop trigger 100% deterministically with a trivial 4-step sequence; there is no race or memory-layout condition to win.\nPR:L - Arena map creation requires CAP_BPF, but bpf_token_capable() resolves via ns_capable(token-\u003euserns, CAP_BPF), so a delegated BPF token or a container granted CAP_BPF lets an otherwise unprivileged user reach it; this is a delegatable capability, not init-namespace root.\nUI:N - The attacker performs the entire sequence \u2014 map create, mmap, page touch, fd close \u2014 in their own process. No victim action is required.\nS:U - The infinite loop, out-of-bounds page-table walk, and page frees all occur within the kernel\u0027s own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - Once pte++ walks past the end of the PTE page, arbitrary kernel memory is read and interpreted as page-table entries, and __free_page() on garbage-derived struct pages releases in-use pages for reallocation, which is leverageable for disclosure of other tasks\u0027 data.\nI:H - existing_page_cb() calls __free_page() on struct page pointers decoded from out-of-bounds memory, corrupting page refcounts and prematurely freeing live pages \u2014 a use-after-free primitive suitable for heap grooming and control-flow hijacking.\nA:H - The `while (addr += PAGE_SIZE, addr != end)` loop can never terminate, producing a soft lockup/RCU stall inside a lazy-MMU section on a system workqueue, hanging the machine; the stray page frees compound this into a panic."
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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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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