workqueue: Fix NULL current_pwq deref in flush dependency check

{
  "id": "dcd8e2d50c3e82a84928306796af5ba21e1d3f553ed7c876e7bec474f47ebe16",
  "url": "https://osv.dev/vulnerability/CVE-2026-98537",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "workqueue: Fix NULL current_pwq deref in flush dependency check",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: workqueue: Fix NULL current_pwq deref in flush dependency check check_flush_dependency() uses current_wq_worker() to determine whether the caller is a workqueue worker and then dereferences worker->current_pwq to test whether the current workqueue is WQ_MEM_RECLAIM. current_wq_worker() only means that %current has PF_WQ_WORKER set. A kworker can reach check_flush_dependency() while it is not executing a work item. One such path is worker_thread() acting as the pool manager, where create_worker() does GFP_KERNEL allocation and the allocation path invokes the OOM notifier. In that state worker->current_pwq is NULL because current_pwq is set only by process_one_work() and cleared again after the work function returns. [ 416.760634][ T375] Call trace: [ 416.760638][ T375] check_flush_dependency+0x80/0x120 (P) [ 416.760648][ T375] __flush_work+0x98/0x224 [ 416.760657][ T375] flush_work+0x30/0x44 [ 416.760665][ T375] ... [ 416.760710][ T375] blocking_notifier_call_chain+0x58/0xa0 [ 416.760719][ T375] out_of_memory+0xb4/0x458 [ 416.760730][ T375] __alloc_pages_may_oom+0x11c/0x1a8 [ 416.760739][ T375] __alloc_pages_slowpath+0x314/0x46c [ 416.760746][ T375] __alloc_frozen_pages_noprof+0x110/0x1a4 [ 416.760753][ T375] new_slab+0x12c/0x484 [ 416.760759][ T375] ___slab_alloc+0x7a8/0xc7c [ 416.760765][ T375] __slab_alloc+0x74/0xd8 [ 416.760772][ T375] __kmalloc_cache_node_noprof+0x2ac/0x304 [ 416.760779][ T375] alloc_work",
    "evidence": "osv:CVE-2026-98537",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.10.271",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.15.222",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.189",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.158",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.112",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.55",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.9",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98537",
      "aliases": [
        "CVE-2026-98537"
      ],
      "affected": [
        {
          "ranges": [
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              "type": "GIT",
              "events": [
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                  "fixed": "8ffececcb88262389b4f91fed0fe4884b68204bc"
                },
                {
                  "fixed": "9bb739a5c5a570c28a62afb98e9326e2a49743c1"
                },
                {
                  "fixed": "cc190a6a1d20b87e6a9435202fc2a3bd84c79fb3"
                },
                {
                  "fixed": "513121e69388604619ea8c0ee07e86a3d1b5b5dc"
                },
                {
                  "fixed": "0c6b9b1e295aeff1132ac7aa738148cc65f06485"
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                {
                  "fixed": "1dccf5dc2f8fe688270b261ca4216e03c6a1e674"
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                {
                  "fixed": "f97e6d0572d1b39998e053732332bc3cfdd0b9aa"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98537.json"
          }
        },
        {
          "ranges": [
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              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "4.5.0"
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                {
                  "fixed": "5.10.271"
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            {
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            {
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                {
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98537.json"
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      ],
      "modified": "2026-10-28T02:30:48.671570989Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0c6b9b1e295aeff1132ac7aa738148cc65f06485",
        "https://git.kernel.org/stable/c/1dccf5dc2f8fe688270b261ca4216e03c6a1e674",
        "https://git.kernel.org/stable/c/513121e69388604619ea8c0ee07e86a3d1b5b5dc",
        "https://git.kernel.org/stable/c/8ffececcb88262389b4f91fed0fe4884b68204bc",
        "https://git.kernel.org/stable/c/9bb739a5c5a570c28a62afb98e9326e2a49743c1",
        "https://git.kernel.org/stable/c/cc190a6a1d20b87e6a9435202fc2a3bd84c79fb3",
        "https://git.kernel.org/stable/c/db6365ced4d5855e321f772b240c0e473bcfcdd5",
        "https://git.kernel.org/stable/c/f97e6d0572d1b39998e053732332bc3cfdd0b9aa",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98537.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98537",
        "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/2026/98xxx/CVE-2026-98537.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98537",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 517100,
  "published_at": "2026-10-18T15:18:05.028+00:00"
}