bpf: Cancel special fields on map value recycle

{
  "id": "590dcb4726477dbd66558fd5da70bd4b50601c987718def1c62adb2f916da8f4",
  "url": "https://osv.dev/vulnerability/CVE-2026-74314",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "bpf: Cancel special fields on map value recycle",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: bpf: Cancel special fields on map value recycle Map update and delete paths currently call bpf_obj_free_fields() when a value is being replaced or recycled. That makes field destruction depend on the context of the update/delete operation. For tracing programs this can include NMI context, where referenced kptr destructors, uptr unpinning, and graph root destruction are not generally safe. Introduce bpf_obj_cancel_fields() for the reusable-value path. It only performs NMI-safe cleanup for timer, workqueue, and task_work fields. Fields that need full destruction are left attached to the recycled value and are destroyed by the final cleanup path instead. Switch array and hashtab update/delete/recycle paths to this cancel helper. Keep bpf_obj_free_fields() for final map destruction and for bpf_mem_alloc destructors. Preallocated hashtabs do not have allocator destructors, so teardown continues to walk the normal and extra elements and fully destroy their fields. This deliberately relaxes the eager-free semantics of map update/delete for special fields. Programs that relied on a recycled map slot becoming empty immediately after update/delete were relying on behavior that cannot be implemented safely from every BPF execution context without offloading arbitrary destructors. There is a chance this change breaks programs making assumptions regarding the eager freeing of fields. If so, we can relax semantics to canc",
    "evidence": "osv:CVE-2026-74314",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "7.1.5",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-74314",
      "aliases": [
        "CVE-2026-74314"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                {
                  "fixed": "9ea734e2cc0143d7429ab7dc0b20c85e5836183c"
                },
                {
                  "fixed": "a3a81d247651218e47153f2d2afd7aee236726fd"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "5.18.18"
                },
                {
                  "fixed": "5.19"
                }
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            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "f0462d38589422bc9e27fd3c6343dfeb6b3db2f9"
                }
              ]
            }
          ],
          "versions": [
            "v5.18.19",
            "v5.18.18"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74314.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.19.0"
                },
                {
                  "fixed": "7.1.5"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74314.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:23.762592745Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/9ea734e2cc0143d7429ab7dc0b20c85e5836183c",
        "https://git.kernel.org/stable/c/a3a81d247651218e47153f2d2afd7aee236726fd",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74314.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-74314",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74314.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-74314",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 490275,
  "published_at": "2026-08-15T05:58:12.766+00:00"
}