CVE-2026-97925 (GCVE-0-2026-97925)

Vulnerability from cvelistv5 – Published: 2026-09-25 10:22 – Updated: 2026-09-25 10:22
VLAI
Title
tick/broadcast: Plug clockevents replacement race
Summary
In the Linux kernel, the following vulnerability has been resolved: tick/broadcast: Plug clockevents replacement race 朱恺乾 reported and decoded the following race condition when a broadcast device is replaced: CPUA CPUB __tick_broadcast_oneshot_control() bc = tick_broadcast_device.evtdev; tick_install_broadcast_device(dev) clockevents_exchange_device(cur, dev) shutdown(cur); detach(cur); cur->handler = noop; tick_broadcast_device.evtdev = dev; tick_broadcast_set_event(bc, next_event); <- FAIL: arms a detached device. If the original broadcast device has a restricted interrupt affinity mask and the last CPU in that mask goes offline then the BUG() in tick_cleanup_dead_cpu() triggers because the clockevent device is not in detached state. The reason for this is that tick_install_broadcast_device() is not serialized vs. tick broadcast operations. The obvious cure is to serialize tick_install_broadcast_device() with tick_broadcast_lock against a concurrent tick broadcast operation. That requires to split clockevents_exchange_device() into two parts, one which does the exchange, shutdown and detach operation and the other which drops the module reference count. This is required because the module reference cannot be dropped while holding tick_broadcast_lock. Let clockevents_exchange_device() do both operations as before, but let the broadcast device code take the two step approach and do the device exchange under tick_broadcast_lock and drop the module reference count after releasing it.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: f8381cba04ba8173fd5a2b8e5cd8b3290ee13a98 , < 3da55616db2b6b7d9caa3b7ff1e8983224e0ed52 (git)
Affected: f8381cba04ba8173fd5a2b8e5cd8b3290ee13a98 , < 3525b94b2f258e0b99d1ee5a82a80b51bc1cc818 (git)
Affected: f8381cba04ba8173fd5a2b8e5cd8b3290ee13a98 , < 292b7a8ed84032cfdfc9076a690360f7d3f640d4 (git)
Affected: f8381cba04ba8173fd5a2b8e5cd8b3290ee13a98 , < 113a9796effe3376d2ec5aabcca1fef4fef4cd62 (git)
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Linux Linux Affected: 2.6.21
Unaffected: 0 , < 2.6.21 (semver)
Unaffected: 6.12.111 , ≤ 6.12.* (semver)
Unaffected: 6.18.53 , ≤ 6.18.* (semver)
Unaffected: 7.2.7 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc3 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/time/clockevents.c",
            "kernel/time/tick-broadcast.c",
            "kernel/time/tick-internal.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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          "product": "Linux",
          "programFiles": [
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.21"
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              "version": "0",
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              "versionType": "semver"
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              "versionType": "semver"
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              "version": "7.2.7",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.3-rc3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
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              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.111",
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntick/broadcast: Plug clockevents replacement race\n\n\u6731\u607a\u4e7e reported and decoded the following race condition when a broadcast\ndevice is replaced:\n\nCPUA\t\t\t\t\tCPUB\n __tick_broadcast_oneshot_control()\n   bc = tick_broadcast_device.evtdev;\n\t\t\t\t\ttick_install_broadcast_device(dev)\n        \t\t\t\tclockevents_exchange_device(cur, dev)\n\t\t\t\t\t   shutdown(cur);\n\t\t\t\t\t   detach(cur);\n\t\t\t\t\t   cur-\u003ehandler = noop;\n\t\t\t\t\t   tick_broadcast_device.evtdev = dev;\n\n  tick_broadcast_set_event(bc, next_event); \u003c- FAIL: arms a detached device.\n\nIf the original broadcast device has a restricted interrupt affinity mask\nand the last CPU in that mask goes offline then the BUG() in\ntick_cleanup_dead_cpu() triggers because the clockevent device is not in\ndetached state.\n\nThe reason for this is that tick_install_broadcast_device() is not\nserialized vs. tick broadcast operations.\n\nThe obvious cure is to serialize tick_install_broadcast_device() with\ntick_broadcast_lock against a concurrent tick broadcast operation.\n\nThat requires to split clockevents_exchange_device() into two parts, one\nwhich does the exchange, shutdown and detach operation and the other which\ndrops the module reference count. This is required because the module\nreference cannot be dropped while holding tick_broadcast_lock.\n\nLet clockevents_exchange_device() do both operations as before, but let the\nbroadcast device code take the two step approach and do the device\nexchange under tick_broadcast_lock and drop the module reference count\nafter releasing it."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-25T10:22:43.552Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/3da55616db2b6b7d9caa3b7ff1e8983224e0ed52"
        },
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          "url": "https://git.kernel.org/stable/c/3525b94b2f258e0b99d1ee5a82a80b51bc1cc818"
        },
        {
          "url": "https://git.kernel.org/stable/c/292b7a8ed84032cfdfc9076a690360f7d3f640d4"
        },
        {
          "url": "https://git.kernel.org/stable/c/113a9796effe3376d2ec5aabcca1fef4fef4cd62"
        }
      ],
      "title": "tick/broadcast: Plug clockevents replacement race",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-97925",
    "datePublished": "2026-09-25T10:22:43.552Z",
    "dateReserved": "2026-09-25T10:18:58.202Z",
    "dateUpdated": "2026-09-25T10:22:43.552Z",
    "state": "PUBLISHED"
  },
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      "date": "2026-09-28",
      "epss": "0.002",
      "percentile": "0.08801"
    },
    "microsoft_vex": {
      "current_release_date": "2026-09-28T01:57:10.000Z",
      "cve": "CVE-2026-97925",
      "id": "msrc_CVE-2026-97925",
      "initial_release_date": "2026-09-28T01:57:10.000Z",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "tick/broadcast: Plug clockevents replacement race",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-97925.json",
      "version": "1"
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    "nvd": {
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                "product": "Linux",
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                  "kernel/time/tick-broadcast.c",
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                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
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        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntick/broadcast: Plug clockevents replacement race\n\n\u6731\u607a\u4e7e reported and decoded the following race condition when a broadcast\ndevice is replaced:\n\nCPUA\t\t\t\t\tCPUB\n __tick_broadcast_oneshot_control()\n   bc = tick_broadcast_device.evtdev;\n\t\t\t\t\ttick_install_broadcast_device(dev)\n        \t\t\t\tclockevents_exchange_device(cur, dev)\n\t\t\t\t\t   shutdown(cur);\n\t\t\t\t\t   detach(cur);\n\t\t\t\t\t   cur-\u003ehandler = noop;\n\t\t\t\t\t   tick_broadcast_device.evtdev = dev;\n\n  tick_broadcast_set_event(bc, next_event); \u003c- FAIL: arms a detached device.\n\nIf the original broadcast device has a restricted interrupt affinity mask\nand the last CPU in that mask goes offline then the BUG() in\ntick_cleanup_dead_cpu() triggers because the clockevent device is not in\ndetached state.\n\nThe reason for this is that tick_install_broadcast_device() is not\nserialized vs. tick broadcast operations.\n\nThe obvious cure is to serialize tick_install_broadcast_device() with\ntick_broadcast_lock against a concurrent tick broadcast operation.\n\nThat requires to split clockevents_exchange_device() into two parts, one\nwhich does the exchange, shutdown and detach operation and the other which\ndrops the module reference count. This is required because the module\nreference cannot be dropped while holding tick_broadcast_lock.\n\nLet clockevents_exchange_device() do both operations as before, but let the\nbroadcast device code take the two step approach and do the device\nexchange under tick_broadcast_lock and drop the module reference count\nafter releasing it."
          }
        ],
        "id": "CVE-2026-97925",
        "lastModified": "2026-09-25T11:17:19.680",
        "metrics": {},
        "published": "2026-09-25T11:17:19.680",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
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  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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