workqueue: Fix spruious data race in __flush_work()

{
  "id": "daa152e1c75383f566ccfb87af5a8cb7b05831acb32a456e79d83b154f934744",
  "url": "https://osv.dev/vulnerability/CVE-2024-46704",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "workqueue: Fix spruious data race in __flush_work()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: workqueue: Fix spruious data race in __flush_work() When flushing a work item for cancellation, __flush_work() knows that it exclusively owns the work item through its PENDING bit. 134874e2eee9 (\"workqueue: Allow cancel_work_sync() and disable_work() from atomic contexts on BH work items\") added a read of @work->data to determine whether to use busy wait for BH work items that are being canceled. While the read is safe when @from_cancel, @work->data was read before testing @from_cancel to simplify code structure: data = *work_data_bits(work); if (from_cancel && !WARN_ON_ONCE(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_BH)) { While the read data was never used if !@from_cancel, this could trigger KCSAN data race detection spuriously: ================================================================== BUG: KCSAN: data-race in __flush_work / __flush_work write to 0xffff8881223aa3e8 of 8 bytes by task 3998 on cpu 0: instrument_write include/linux/instrumented.h:41 [inline] ___set_bit include/asm-generic/bitops/instrumented-non-atomic.h:28 [inline] insert_wq_barrier kernel/workqueue.c:3790 [inline] start_flush_work kernel/workqueue.c:4142 [inline] __flush_work+0x30b/0x570 kernel/workqueue.c:4178 flush_work kernel/workqueue.c:4229 [inline] ... read to 0xffff8881223aa3e8 of 8 bytes by task 50 on cpu 1: __flush_work+0x42a/0x570 kernel/workqueue.c:4188 flush_work kernel/workqueue.c:4229 [inline] flush_delayed_work+0x6",
    "evidence": "osv:CVE-2024-46704",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.10.7",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2024-46704",
      "aliases": [
        "CVE-2024-46704"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "134874e2eee9380c2700411d4844cbc29297bc01"
                },
                {
                  "fixed": "91d09642127a32fde231face2ff489af70eef316"
                },
                {
                  "fixed": "8bc35475ef1a23b0e224f3242eb11c76cab0ea88"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-46704.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.10.0"
                },
                {
                  "fixed": "6.10.7"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-46704.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:24.615285828Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/8bc35475ef1a23b0e224f3242eb11c76cab0ea88",
        "https://git.kernel.org/stable/c/91d09642127a32fde231face2ff489af70eef316",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/46xxx/CVE-2024-46704.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-46704",
        "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/2024/46xxx/CVE-2024-46704.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-46704",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 490818,
  "published_at": "2024-09-13T06:27:31.822+00:00"
}