CVE-2026-64250 (GCVE-0-2026-64250)

Vulnerability from cvelistv5 – Published: 2026-07-24 15:31 – Updated: 2026-08-17 04:52
VLAI
Title
LoongArch: Report dying CPU to RCU in stop_this_cpu()
Summary
In the Linux kernel, the following vulnerability has been resolved: LoongArch: Report dying CPU to RCU in stop_this_cpu() This is a port of MIPS commit 9f3f3bdc6d9dac1 ("MIPS: smp: report dying CPU to RCU in stop_this_cpu()"). smp_send_stop() parks all secondary CPUs in stop_this_cpu(). And the function marks the CPU offline for the scheduler via set_cpu_online(false) but never informs RCU, so RCU keeps expecting a quiescent state from CPUs that are now spinning forever with interrupts disabled. As long as nothing waits for an RCU grace period after smp_send_stop() this is harmless, which is why it went unnoticed. However, since commit 91840be8f710370 ("irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT"), irq_work_sync() calls synchronize_rcu() on architectures without an irq_work self-IPI, i.e. where arch_irq_work_has_interrupt() returns false. Any irq_work_sync() issued in the reboot/shutdown/halt path after smp_send_stop() then blocks on a grace period that can never complete, hanging the reboot: WARNING: CPU: 0 PID: 15 at kernel/irq_work.c:144 irq_work_queue_on ... rcu: INFO: rcu_sched detected stalls on CPUs/tasks: rcu: Offline CPU 1 blocking current GP. rcu: Offline CPU 2 blocking current GP. rcu: Offline CPU 3 blocking current GP. This issue needs some hacks to reproduce, and it was not noticed on LoongArch because arch_irq_work_has_interrupt() usually returns true. Call rcutree_report_cpu_dead() once interrupts are disabled, mirroring the generic CPU-hotplug offline path, so RCU stops waiting on the parked CPUs and grace periods can still complete. LoongArch shuts down all CPUs here without going through the CPU-hotplug mechanism, so this report is not otherwise issued.
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6639 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 2dc79362302922cb18f35e262712b5e58de65442 , < 262dadc619e69ebeb97affd334cd1078a9704e98 (git)
Affected: eef4f71b46a9929ac33e968538c9dd5d96a02460 , < 1fa22de588a65880d6fe54c38c87fffe7d519f60 (git)
Affected: 684a78183c54c23e70d1cba320f7fc184604210b , < a0269e928728f970c782319fee53d92d4ea4e512 (git)
Affected: 18c0456ea2615b1a743a6db739c74411c3b42bc6 , < 90e254f18b8c224460082329dd5c42fd30995c2f (git)
Affected: 91840be8f710370607f949a627e070896faeddb8 , < 0833b2b84c2fc1387f8165f0cbf6a02d67f647a5 (git)
Affected: 91840be8f710370607f949a627e070896faeddb8 , < f2539c56c74691e7a88af6372ba2b48c06ed2fe4 (git)
Affected: 81b582784518196eff1050212a046bc29d3a05dd (git)
Affected: 6.1.175 , < 6.1.178 (semver)
Affected: 6.6.142 , < 6.6.145 (semver)
Affected: 6.12.92 , < 6.12.95 (semver)
Affected: 6.18.34 , < 6.18.38 (semver)
Affected: 7.0.11 , < 7.1 (semver)
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Linux Linux Affected: 7.1
Unaffected: 0 , < 7.1 (semver)
Unaffected: 6.1.178 , ≤ 6.1.* (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.95 , ≤ 6.12.* (semver)
Unaffected: 6.18.38 , ≤ 6.18.* (semver)
Unaffected: 7.1.3 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nLoongArch: Report dying CPU to RCU in stop_this_cpu()\n\nThis is a port of MIPS commit 9f3f3bdc6d9dac1 (\"MIPS: smp: report dying\nCPU to RCU in stop_this_cpu()\"). smp_send_stop() parks all secondary\nCPUs in stop_this_cpu(). And the function marks the CPU offline for the\nscheduler via set_cpu_online(false) but never informs RCU, so RCU keeps\nexpecting a quiescent state from CPUs that are now spinning forever with\ninterrupts disabled.\n\nAs long as nothing waits for an RCU grace period after smp_send_stop()\nthis is harmless, which is why it went unnoticed. However, since commit\n91840be8f710370 (\"irq_work: Fix use-after-free in irq_work_single() on\nPREEMPT_RT\"), irq_work_sync() calls synchronize_rcu() on architectures\nwithout an irq_work self-IPI, i.e. where arch_irq_work_has_interrupt()\nreturns false. Any irq_work_sync() issued in the reboot/shutdown/halt\npath after smp_send_stop() then blocks on a grace period that can never\ncomplete, hanging the reboot:\n\n  WARNING: CPU: 0 PID: 15 at kernel/irq_work.c:144 irq_work_queue_on\n  ...\n  rcu: INFO: rcu_sched detected stalls on CPUs/tasks:\n  rcu: Offline CPU 1 blocking current GP.\n  rcu: Offline CPU 2 blocking current GP.\n  rcu: Offline CPU 3 blocking current GP.\n\nThis issue needs some hacks to reproduce, and it was not noticed on\nLoongArch because arch_irq_work_has_interrupt() usually returns true.\n\nCall rcutree_report_cpu_dead() once interrupts are disabled, mirroring\nthe generic CPU-hotplug offline path, so RCU stops waiting on the parked\nCPUs and grace periods can still complete. LoongArch shuts down all CPUs\nhere without going through the CPU-hotplug mechanism, so this report is\nnot otherwise issued."
          },
          {
            "lang": "es",
            "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nLoongArch: Informar CPU moribunda a RCU en stop_this_cpu()\n\nEste es un puerto del commit MIPS 9f3f3bdc6d9dac1 (\u2019MIPS: smp: informar CPU moribunda a RCU en stop_this_cpu()\u2019). smp_send_stop() aparca todas las CPUs secundarias en stop_this_cpu(). Y la funci\u00f3n marca la CPU como fuera de l\u00ednea para el planificador a trav\u00e9s de set_cpu_online(false) pero nunca informa a RCU, por lo que RCU sigue esperando un estado de reposo de CPUs que ahora est\u00e1n girando indefinidamente con las interrupciones deshabilitadas.\n\nMientras nada espere un per\u00edodo de gracia de RCU despu\u00e9s de smp_send_stop(), esto es inofensivo, raz\u00f3n por la cual pas\u00f3 desapercibido. Sin embargo, desde el commit 91840be8f710370 (\u2019irq_work: Corregir uso despu\u00e9s de liberaci\u00f3n en irq_work_single() en PREEMPT_RT\u2019), irq_work_sync() llama a synchronize_rcu() en arquitecturas sin un auto-IPI de irq_work, es decir, donde arch_irq_work_has_interrupt() devuelve falso. Cualquier irq_work_sync() emitido en la ruta de reinicio/apagado/detenci\u00f3n despu\u00e9s de smp_send_stop() entonces se bloquea en un per\u00edodo de gracia que nunca puede completarse, colgando el reinicio:\n\n  ADVERTENCIA: CPU: 0 PID: 15 en kernel/irq_work.c:144 irq_work_queue_on\n  ...\n  rcu: INFO: rcu_sched detect\u00f3 bloqueos en CPUs/tareas:\n  rcu: CPU fuera de l\u00ednea 1 bloqueando GP actual.\n  rcu: CPU fuera de l\u00ednea 2 bloqueando GP actual.\n  rcu: CPU fuera de l\u00ednea 3 bloqueando GP actual.\n\nEste problema necesita algunos trucos para reproducirse, y no fue notado en LoongArch porque arch_irq_work_has_interrupt() usualmente devuelve verdadero.\n\nLlamar a rcutree_report_cpu_dead() una vez que las interrupciones est\u00e1n deshabilitadas, reflejando la ruta gen\u00e9rica de desconexi\u00f3n de CPU-hotplug, para que RCU deje de esperar en las CPUs aparcadas y los per\u00edodos de gracia a\u00fan puedan completarse. LoongArch apaga todas las CPUs aqu\u00ed sin pasar por el mecanismo de CPU-hotplug, por lo que este informe no se emite de otra manera."
          }
        ],
        "id": "CVE-2026-64250",
        "lastModified": "2026-11-08T16:10:00.183",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 5.5,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 1.8,
              "impactScore": 3.6,
              "source": "nvd@nist.gov",
              "type": "Primary"
            }
          ]
        },
        "published": "2026-07-24T16:16:54.577",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/0833b2b84c2fc1387f8165f0cbf6a02d67f647a5"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/1fa22de588a65880d6fe54c38c87fffe7d519f60"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/262dadc619e69ebeb97affd334cd1078a9704e98"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/90e254f18b8c224460082329dd5c42fd30995c2f"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/a0269e928728f970c782319fee53d92d4ea4e512"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/f2539c56c74691e7a88af6372ba2b48c06ed2fe4"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Analyzed",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "NVD-CWE-noinfo"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-11-07T11:21:35+00:00",
      "cve": "CVE-2026-64250",
      "id": "CVE-2026-64250",
      "initial_release_date": "2026-07-24T00:00:00+00:00",
      "product_status:known_not_affected": "200",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: LoongArch: Report dying CPU to RCU in stop_this_cpu()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64250.json",
      "version": "3"
    }
  }
}



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