{"id":"CVE-2026-64250","state":"PUBLISHED","title":"LoongArch: Report dying CPU to RCU in stop_this_cpu()","description":"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.","publishedAt":"2026-07-24T15:31:17.021Z","updatedAt":"2026-08-17T04:52:01.823Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"2dc79362302922cb18f35e262712b5e58de65442","status":"affected","lessThan":"262dadc619e69ebeb97affd334cd1078a9704e98","versionType":"git"},{"version":"eef4f71b46a9929ac33e968538c9dd5d96a02460","status":"affected","lessThan":"1fa22de588a65880d6fe54c38c87fffe7d519f60","versionType":"git"},{"version":"684a78183c54c23e70d1cba320f7fc184604210b","status":"affected","lessThan":"a0269e928728f970c782319fee53d92d4ea4e512","versionType":"git"},{"version":"18c0456ea2615b1a743a6db739c74411c3b42bc6","status":"affected","lessThan":"90e254f18b8c224460082329dd5c42fd30995c2f","versionType":"git"},{"version":"91840be8f710370607f949a627e070896faeddb8","status":"affected","lessThan":"0833b2b84c2fc1387f8165f0cbf6a02d67f647a5","versionType":"git"},{"version":"91840be8f710370607f949a627e070896faeddb8","status":"affected","lessThan":"f2539c56c74691e7a88af6372ba2b48c06ed2fe4","versionType":"git"},{"version":"81b582784518196eff1050212a046bc29d3a05dd","status":"affected","versionType":"git"},{"version":"6.1.175","status":"affected","lessThan":"6.1.178","versionType":"semver"},{"version":"6.6.142","status":"affected","lessThan":"6.6.145","versionType":"semver"},{"version":"6.12.92","status":"affected","lessThan":"6.12.95","versionType":"semver"},{"version":"6.18.34","status":"affected","lessThan":"6.18.38","versionType":"semver"},{"version":"7.0.11","status":"affected","lessThan":"7.1","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/loongarch/kernel/smp.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.1","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.95","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.38","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.3","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/loongarch/kernel/smp.c"]}],"references":["https://git.kernel.org/stable/c/262dadc619e69ebeb97affd334cd1078a9704e98","https://git.kernel.org/stable/c/1fa22de588a65880d6fe54c38c87fffe7d519f60","https://git.kernel.org/stable/c/a0269e928728f970c782319fee53d92d4ea4e512","https://git.kernel.org/stable/c/90e254f18b8c224460082329dd5c42fd30995c2f","https://git.kernel.org/stable/c/0833b2b84c2fc1387f8165f0cbf6a02d67f647a5","https://git.kernel.org/stable/c/f2539c56c74691e7a88af6372ba2b48c06ed2fe4"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64250.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64250","state":"PUBLISHED","datePublished":"2026-07-24T15:31:17.021Z","dateUpdated":"2026-08-17T04:52:01.823Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.773Z"},"containers":{"cna":{"title":"LoongArch: Report dying CPU to RCU in stop_this_cpu()","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"2dc79362302922cb18f35e262712b5e58de65442","status":"affected","lessThan":"262dadc619e69ebeb97affd334cd1078a9704e98","versionType":"git"},{"version":"eef4f71b46a9929ac33e968538c9dd5d96a02460","status":"affected","lessThan":"1fa22de588a65880d6fe54c38c87fffe7d519f60","versionType":"git"},{"version":"684a78183c54c23e70d1cba320f7fc184604210b","status":"affected","lessThan":"a0269e928728f970c782319fee53d92d4ea4e512","versionType":"git"},{"version":"18c0456ea2615b1a743a6db739c74411c3b42bc6","status":"affected","lessThan":"90e254f18b8c224460082329dd5c42fd30995c2f","versionType":"git"},{"version":"91840be8f710370607f949a627e070896faeddb8","status":"affected","lessThan":"0833b2b84c2fc1387f8165f0cbf6a02d67f647a5","versionType":"git"},{"version":"91840be8f710370607f949a627e070896faeddb8","status":"affected","lessThan":"f2539c56c74691e7a88af6372ba2b48c06ed2fe4","versionType":"git"},{"version":"81b582784518196eff1050212a046bc29d3a05dd","status":"affected","versionType":"git"},{"version":"6.1.175","status":"affected","lessThan":"6.1.178","versionType":"semver"},{"version":"6.6.142","status":"affected","lessThan":"6.6.145","versionType":"semver"},{"version":"6.12.92","status":"affected","lessThan":"6.12.95","versionType":"semver"},{"version":"6.18.34","status":"affected","lessThan":"6.18.38","versionType":"semver"},{"version":"7.0.11","status":"affected","lessThan":"7.1","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/loongarch/kernel/smp.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.1","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.95","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.38","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.3","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/loongarch/kernel/smp.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/262dadc619e69ebeb97affd334cd1078a9704e98"},{"url":"https://git.kernel.org/stable/c/1fa22de588a65880d6fe54c38c87fffe7d519f60"},{"url":"https://git.kernel.org/stable/c/a0269e928728f970c782319fee53d92d4ea4e512"},{"url":"https://git.kernel.org/stable/c/90e254f18b8c224460082329dd5c42fd30995c2f"},{"url":"https://git.kernel.org/stable/c/0833b2b84c2fc1387f8165f0cbf6a02d67f647a5"},{"url":"https://git.kernel.org/stable/c/f2539c56c74691e7a88af6372ba2b48c06ed2fe4"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:52:01.823Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.175","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.142","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12.92","versionEndExcluding":"6.12.95"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.18.34","versionEndExcluding":"6.18.38"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.1.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.0.11"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}