CVE-2026-64250

/// Technical description

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 neve

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References