tracing: Fix use-after-free freeing trigger private data

{
  "id": "c16b41364b4864e943dd479530ccbd5e4572d6642583a217c21b8735aa09fd62",
  "url": "https://osv.dev/vulnerability/CVE-2026-68283",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "tracing: Fix use-after-free freeing trigger private data",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: tracing: Fix use-after-free freeing trigger private data Commit 61d445af0a7c (\"tracing: Add bulk garbage collection of freeing event_trigger_data\") moved the kfree() of event_trigger_data to a kthread that runs tracepoint_synchronize_unregister() before freeing. That removed the synchronization the trigger .free callbacks used to get implicitly and inline from trigger_data_free(). event_hist_trigger_free(), event_hist_trigger_named_free() and event_enable_trigger_free() free their satellite data (hist_data, cmd_ops, enable_data) right after trigger_data_free() returns. With the synchronization now deferred to the kthread, a concurrent tracepoint handler can still reach that data through the list_del_rcu()'d trigger, causing a use-after-free. The histogram teardown must stay synchronous: remove_hist_vars() and unregister_field_var_hists() have to detach a synthetic event from the histogram before the trigger-removal write returns, otherwise a following command races in and the synthetic-event removal fails with -EBUSY, as the trigger-synthetic-eprobe.tc selftest catches. Make those callbacks wait with the correct barrier - tracepoint_synchronize_unregister(), matching the free kthread - before freeing. The enable trigger has no such synchronous requirement, and a blocking synchronize there would re-serialize the path that commit deliberately deferred. Give it an optional private_data_free() callback that the f",
    "evidence": "osv:CVE-2026-68283",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "7.1.6",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-68283",
      "aliases": [
        "CVE-2026-68283"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/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": [
                {
                  "introduced": "61d445af0a7c70018111919e47beaaee15653f2f"
                },
                {
                  "fixed": "b9c8a1400a3bf633f32820d184f3e05fed0f4af7"
                },
                {
                  "fixed": "79097812153b826fc156a2930ec8a90ed9edf4a2"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68283.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.1.6"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68283.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:28.987244057Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/79097812153b826fc156a2930ec8a90ed9edf4a2",
        "https://git.kernel.org/stable/c/b9c8a1400a3bf633f32820d184f3e05fed0f4af7",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68283.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-68283",
        "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/2026/68xxx/CVE-2026-68283.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-68283",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 495895,
  "published_at": "2026-08-10T12:02:15.088+00:00"
}