FKIE_CVE-2026-64248

Vulnerability from fkie_nvd - Published: 2026-07-24 16:16 - Updated: 2026-11-08 16:10
Severity
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: MIPS: smp: report dying CPU to RCU in stop_this_cpu() smp_send_stop() parks all secondary CPUs in stop_this_cpu(). 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. Since commit 91840be8f710 ("irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT") however, irq_work_sync() calls synchronize_rcu() on architectures without an irq_work self-IPI, i.e. where arch_irq_work_has_interrupt() returns false. That is the asm-generic default used by MIPS. Any irq_work_sync() issued in the reboot/shutdown 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 was noticed on several Realtek MIPS switch SoCs (MIPS interAptiv) and came up during kernel bump downstream in OpenWrt from 6.18.33 to 6.18.34, after the backport of the patch to the 6.18 stable branch. The patch also has been backported all the way back to 6.1. 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. MIPS shuts down all CPUs here without going through the CPU-hotplug mechanism, so this report is not otherwise issued. Reporting a dying CPU to RCU outside the regular hotplug offline path is not unprecedented: arm64 does the same in cpu_die_early(). There it is an exception for a CPU that was coming online and is aborting bringup, rather than the default shutdown action as on MIPS.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6eda71977ee11c222f8ad4cae4d18d50448e56f4Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9f3f3bdc6d9dac1a5a8262ee7ad0f2ff1527a7e7Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9fef09df42df55ab819b285ea892e0fc1b95a9c4Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e1919d026706544cb6e7251ec06e908edd6f34eePatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f8a1ef884013dc99f712d3eb75624c7cd3fd94f6Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f9b57a0015c241274651f4b36627f56b1b5a8651Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel 7.1
To clipboard 

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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nMIPS: smp: report dying CPU to RCU in stop_this_cpu()\n\nsmp_send_stop() parks all secondary CPUs in stop_this_cpu(). The function\nmarks the CPU offline for the scheduler via set_cpu_online(false) but\nnever informs RCU, so RCU keeps expecting a quiescent state from CPUs\nthat are now spinning forever with interrupts 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. Since commit\n91840be8f710 (\"irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT\")\nhowever, irq_work_sync() calls synchronize_rcu() on architectures without\nan irq_work self-IPI, i.e. where arch_irq_work_has_interrupt() returns\nfalse. That is the asm-generic default used by MIPS. Any irq_work_sync()\nissued in the reboot/shutdown path after smp_send_stop() then blocks on\na grace period that can never complete, 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 was noticed on several Realtek MIPS switch SoCs (MIPS\ninterAptiv) and came up during kernel bump downstream in OpenWrt from\n6.18.33 to 6.18.34, after the backport of the patch to the 6.18 stable\nbranch. The patch also has been backported all the way back to 6.1.\n\nCall rcutree_report_cpu_dead() once interrupts are disabled, mirroring the\ngeneric CPU-hotplug offline path, so RCU stops waiting on the parked CPUs\nand grace periods can still complete. MIPS shuts down all CPUs here\nwithout going through the CPU-hotplug mechanism, so this report is not\notherwise issued. Reporting a dying CPU to RCU outside the regular hotplug\noffline path is not unprecedented: arm64 does the same in cpu_die_early().\nThere it is an exception for a CPU that was coming online and is aborting\nbringup, rather than the default shutdown action as on MIPS."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nMIPS: smp: informar CPU moribunda a RCU en stop_this_cpu()\n\nsmp_send_stop() estaciona todas las CPUs secundarias en stop_this_cpu(). 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 las 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 91840be8f710 (\u2019irq_work: Fix use-after-free in irq_work_single() on 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. Ese es el valor predeterminado asm-generic utilizado por MIPS. Cualquier irq_work_sync() emitido en la ruta de reinicio/apagado despu\u00e9s de smp_send_stop() se bloquea entonces 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 1 fuera de l\u00ednea bloqueando GP actual.\n  rcu: CPU 2 fuera de l\u00ednea bloqueando GP actual.\n  rcu: CPU 3 fuera de l\u00ednea bloqueando GP actual.\n\nEste problema fue notado en varios SoCs de switch MIPS de Realtek (MIPS interAptiv) y surgi\u00f3 durante la actualizaci\u00f3n del kernel en OpenWrt de 6.18.33 a 6.18.34, despu\u00e9s del backport del parche a la rama estable 6.18. El parche tambi\u00e9n ha sido backporteado hasta la versi\u00f3n 6.1.\n\nLlamar a rcutree_report_cpu_dead() una vez que las interrupciones est\u00e9n deshabilitadas, reflejando la ruta gen\u00e9rica de desconexi\u00f3n de CPU-hotplug, para que RCU deje de esperar en las CPUs estacionadas y los per\u00edodos de gracia a\u00fan puedan completarse. MIPS 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. Informar una CPU moribunda a RCU fuera de la ruta regular de desconexi\u00f3n de hotplug no tiene precedentes: arm64 hace lo mismo en cpu_die_early(). All\u00ed es una excepci\u00f3n para una CPU que estaba entrando en l\u00ednea y est\u00e1 abortando el inicio, en lugar de la acci\u00f3n de apagado predeterminada como en MIPS."
    }
  ],
  "id": "CVE-2026-64248",
  "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": "2026-07-24T16:16:54.280",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/6eda71977ee11c222f8ad4cae4d18d50448e56f4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/9f3f3bdc6d9dac1a5a8262ee7ad0f2ff1527a7e7"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/9fef09df42df55ab819b285ea892e0fc1b95a9c4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/e1919d026706544cb6e7251ec06e908edd6f34ee"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/f8a1ef884013dc99f712d3eb75624c7cd3fd94f6"
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    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
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      "url": "https://git.kernel.org/stable/c/f9b57a0015c241274651f4b36627f56b1b5a8651"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}



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