CVE-2026-64250

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> LoongArch: Report dying CPU to RCU in stop_this_cpu()<br /> <br /> This is a port of MIPS commit 9f3f3bdc6d9dac1 ("MIPS: smp: report dying<br /> CPU to RCU in stop_this_cpu()"). smp_send_stop() parks all secondary<br /> CPUs in stop_this_cpu(). And the function marks the CPU offline for the<br /> scheduler via set_cpu_online(false) but never informs RCU, so RCU keeps<br /> expecting a quiescent state from CPUs that are now spinning forever with<br /> interrupts disabled.<br /> <br /> As long as nothing waits for an RCU grace period after smp_send_stop()<br /> this is harmless, which is why it went unnoticed. However, since commit<br /> 91840be8f710370 ("irq_work: Fix use-after-free in irq_work_single() on<br /> PREEMPT_RT"), irq_work_sync() calls synchronize_rcu() on architectures<br /> without an irq_work self-IPI, i.e. where arch_irq_work_has_interrupt()<br /> returns false. Any irq_work_sync() issued in the reboot/shutdown/halt<br /> path after smp_send_stop() then blocks on a grace period that can never<br /> complete, hanging the reboot:<br /> <br /> WARNING: CPU: 0 PID: 15 at kernel/irq_work.c:144 irq_work_queue_on<br /> ...<br /> rcu: INFO: rcu_sched detected stalls on CPUs/tasks:<br /> rcu: Offline CPU 1 blocking current GP.<br /> rcu: Offline CPU 2 blocking current GP.<br /> rcu: Offline CPU 3 blocking current GP.<br /> <br /> This issue needs some hacks to reproduce, and it was not noticed on<br /> LoongArch because arch_irq_work_has_interrupt() usually returns true.<br /> <br /> Call rcutree_report_cpu_dead() once interrupts are disabled, mirroring<br /> the generic CPU-hotplug offline path, so RCU stops waiting on the parked<br /> CPUs and grace periods can still complete. LoongArch shuts down all CPUs<br /> here without going through the CPU-hotplug mechanism, so this report is<br /> not otherwise issued.