{"id":"CVE-2026-98558","title":"net: flush skb_defer_nodes in dev_cpu_dead()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: flush skb_defer_nodes in dev_cpu_dead()\n\nWhen a CPU goes offline, dev_cpu_dead() drains its softnet queues\n(completion_queue, output_queue, poll_list, process_queu…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 68822bdf76f10c3dc80609d4e2cdc1e847429086 < c68f4157463448a76893223e117170be8374d773","Linux >= 68822bdf76f10c3dc80609d4e2cdc1e847429086 < 06e3f54e8b22040ada01a28343badf1990b4dd7d","Linux 5.19"],"published":"2026-10-18","updated":"2026-10-18","sourceUpdated":"2026-10-18T15:18:25.282Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98558","references":[{"url":"https://git.kernel.org/stable/c/c68f4157463448a76893223e117170be8374d773"},{"url":"https://git.kernel.org/stable/c/06e3f54e8b22040ada01a28343badf1990b4dd7d"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T15:45:12.261Z","slug":"CVE-2026-98558","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet: flush skb_defer_nodes in dev_cpu_dead()\n\nWhen a CPU goes offline, dev_cpu_dead() drains its softnet queues\n(completion_queue, output_queue, poll_list, process_queue, and\ninput_pkt_queue), but leaves net_hotdata.skb_defer_nodes untouched.\n\nIf oldcpu goes offline while holding pending skbs in its\nskb_defer_nodes lists (e.g. below the sysctl_skb_defer_max >> 1 IPI\nthreshold, or if the IPI races with CPU teardown), those skbs remain\nstranded until oldcpu is brought back online. If any of these skbs\nhold page_pool fragments, page_pool_destroy() will stall indefinitely\nwaiting for inflight pages to be returned when a netdev or driver is\ntorn down while oldcpu is offline.\n\nAdditionally, if smp_call_function_single_async() fails in\nkick_defer_list_purge() because the target CPU went offline, reset\ndefer_ipi_scheduled to 0 so future IPI kicks are not blocked when the\nCPU comes back online.\n\nAlso, if oldcpu was the last online CPU on its NUMA node, drain that\nnode's slot across all CPUs so no skbs deferred from that node remain\nstranded on idle remote CPUs (or if the node itself is subsequently\nofflined).\n\nFinally, in skb_attempt_defer_free(), re-check cpu_online(cpu) and\nwhether the caller migrated CPUs after llist_add(), flushing the node\nlist if so, to close the preemption TOCTOU race against CPU/node\nteardown.\n\n## Affected\n\n- `Linux >= 68822bdf76f10c3dc80609d4e2cdc1e847429086 < c68f4157463448a76893223e117170be8374d773`\n- `Linux >= 68822bdf76f10c3dc80609d4e2cdc1e847429086 < 06e3f54e8b22040ada01a28343badf1990b4dd7d`\n- `Linux 5.19`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}