sched/fair: Fix overflow in update_tg_cfs_runnable()

{
  "id": "c96066c8e38a5fa26a9d876e1c87c85b884c44feba37e95de5adf97147647e14",
  "url": "https://osv.dev/vulnerability/CVE-2026-93182",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "sched/fair: Fix overflow in update_tg_cfs_runnable()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: sched/fair: Fix overflow in update_tg_cfs_runnable() A divide-by-zero crash is observed when running hackbench: [14697.488452] CPU: 112 UID: 0 PID: 124791 Comm: hackbench Not tainted 7.1.0-rc2+ [14697.492627] RIP: 0010:propagate_entity_load_avg+0x35f/0x3e0 [14697.506799] [14697.507411] __dequeue_task+0x2b4/0xc70 [14697.508677] dequeue_task_fair+0x36/0x370 [14697.509047] dequeue_task+0x101/0x2f0 [14697.509426] __schedule+0x1b1/0x1a00 [14697.510868] anon_pipe_read+0x3da/0x450 [14697.511400] vfs_read+0x361/0x390 [14697.512053] __x64_sys_read+0x19/0x30 The divide-by-zero happens here: if (scale_load_down(gcfs_rq->load.weight)) { load_sum = div_u64(gcfs_rq->avg.load_sum, scale_load_down(gcfs_rq->load.weight)); } gcfs_rq->load.weight is an insane large value and is truncated to the lower 32 bits by div_u64, which happen to be 0. Using AI for investigation, the cause is a u32 overflow in update_tg_cfs_runnable(), and flat pickup became a victim when using tg_tasks(): u32 new_sum, divider; ... new_sum = se->avg.runnable_avg * divider; <-- boom The following sequence shows how this triggers the crash: propagate_entity_load_avg() update_tg_cfs_runnable() # u32 overflow corrupts runnable_sum __update_load_avg_cfs_rq() ___update_load_avg() # computes insane runnable_avg update_tg_load_avg() # propagates to tg->runnable_avg update_cfs_group() calc_concur_shares() tg_tasks() # long-to-int truncation, negative nr reweight_e",
    "evidence": "osv:CVE-2026-93182",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.188",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.157",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.110",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.52",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.6",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-93182",
      "aliases": [
        "CVE-2026-93182"
      ],
      "affected": [
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                  "fixed": "7cc237e3bc1733928313d2462b413ae441b0eef3"
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                {
                  "fixed": "18fdd0978ec3dda0ff6865cd273e47e022180710"
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                {
                  "fixed": "f94e62d21faad5e244d0874598a4d0ebbc0ea405"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-93182.json"
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-93182.json"
          }
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      ],
      "modified": "2026-10-28T02:30:38.193732595Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/18fdd0978ec3dda0ff6865cd273e47e022180710",
        "https://git.kernel.org/stable/c/39d707097a0820c6e87eff4195f0940e8ff1147e",
        "https://git.kernel.org/stable/c/4f166adb5cb0525d9e32d45729fd8f28c80acbee",
        "https://git.kernel.org/stable/c/69fafae4eb2c9fc9bcff1bcbfcccf5d197434d75",
        "https://git.kernel.org/stable/c/7cc237e3bc1733928313d2462b413ae441b0eef3",
        "https://git.kernel.org/stable/c/f94e62d21faad5e244d0874598a4d0ebbc0ea405",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93182.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-93182",
        "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/2026/93xxx/CVE-2026-93182.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-93182",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 505777,
  "published_at": "2026-09-17T16:12:09.381+00:00"
}