GHSA-WP8X-9RX7-6HVR
Vulnerability from github – Published: 2026-07-24 18:31 – Updated: 2026-07-24 18:31In 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.
{
"affected": [],
"aliases": [
"CVE-2026-64250"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-24T16:16:54Z",
"severity": null
},
"details": "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.",
"id": "GHSA-wp8x-9rx7-6hvr",
"modified": "2026-07-24T18:31:29Z",
"published": "2026-07-24T18:31:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64250"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0833b2b84c2fc1387f8165f0cbf6a02d67f647a5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1fa22de588a65880d6fe54c38c87fffe7d519f60"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/262dadc619e69ebeb97affd334cd1078a9704e98"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/90e254f18b8c224460082329dd5c42fd30995c2f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a0269e928728f970c782319fee53d92d4ea4e512"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f2539c56c74691e7a88af6372ba2b48c06ed2fe4"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Confirmed: The vulnerability has been validated from an analyst's perspective.
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- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.