CVE-2026-98558

In the Linux kernel, the following vulnerability has been resolved:

net: flush skb defer nodes in dev cpu dead()

When a CPU goes offline, dev cpu dead() drains its softnet queues (completion queue, output queue, poll list, process queue, and input pkt queue), but leaves net hotdata.skb defer nodes untouched.

If oldcpu goes offline while holding pending skbs in its skb defer nodes lists (e.g. below the sysctl skb defer max >> 1 IPI threshold, or if the IPI races with CPU teardown), those skbs remain stranded until oldcpu is brought back online. If any of these skbs hold page pool fragments, page pool destroy() will stall indefinitely waiting for inflight pages to be returned when a netdev or driver is torn down while oldcpu is offline.

Additionally, if smp call function single async() fails in kick defer list purge() because the target CPU went offline, reset defer ipi scheduled to 0 so future IPI kicks are not blocked when the CPU comes back online.

Also, if oldcpu was the last online CPU on its NUMA node, drain that node's slot across all CPUs so no skbs deferred from that node remain stranded on idle remote CPUs (or if the node itself is subsequently offlined).

Finally, in skb attempt defer free(), re-check cpu online(cpu) and whether the caller migrated CPUs after llist add(), flushing the node list if so, to close the preemption TOCTOU race against CPU/node teardown.