LoongArch: Report dying CPU to RCU in stop_this_cpu()

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Summary

CVECVE-2026-64250
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-24 16:16:54 UTC
Updated2026-07-24 16:16:54 UTC
DescriptionIn 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.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 2dc79362302922cb18f35e262712b5e58de65442 262dadc619e69ebeb97affd334cd1078a9704e98 git Not specified
CNA Linux Linux affected eef4f71b46a9929ac33e968538c9dd5d96a02460 1fa22de588a65880d6fe54c38c87fffe7d519f60 git Not specified
CNA Linux Linux affected 684a78183c54c23e70d1cba320f7fc184604210b a0269e928728f970c782319fee53d92d4ea4e512 git Not specified
CNA Linux Linux affected 18c0456ea2615b1a743a6db739c74411c3b42bc6 90e254f18b8c224460082329dd5c42fd30995c2f git Not specified
CNA Linux Linux affected 91840be8f710370607f949a627e070896faeddb8 0833b2b84c2fc1387f8165f0cbf6a02d67f647a5 git Not specified
CNA Linux Linux affected 91840be8f710370607f949a627e070896faeddb8 f2539c56c74691e7a88af6372ba2b48c06ed2fe4 git Not specified
CNA Linux Linux affected 81b582784518196eff1050212a046bc29d3a05dd git Not specified
CNA Linux Linux affected 6.1.175 6.1.178 semver Not specified
CNA Linux Linux affected 6.6.142 6.6.145 semver Not specified
CNA Linux Linux affected 6.12.92 6.12.95 semver Not specified
CNA Linux Linux affected 6.18.34 6.18.38 semver Not specified
CNA Linux Linux affected 7.0.11 7.1 semver Not specified
CNA Linux Linux affected 7.1 Not specified
CNA Linux Linux unaffected 7.1 semver Not specified
CNA Linux Linux unaffected 6.1.178 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.145 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.95 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.38 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.3 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/0833b2b84c2fc1387f8165f0cbf6a02d67f647a5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/90e254f18b8c224460082329dd5c42fd30995c2f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/262dadc619e69ebeb97affd334cd1078a9704e98 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f2539c56c74691e7a88af6372ba2b48c06ed2fe4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a0269e928728f970c782319fee53d92d4ea4e512 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/1fa22de588a65880d6fe54c38c87fffe7d519f60 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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