CVE-2026-64207

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

net/sched: dualpi2: fix GSO backlog accounting

When DualPI2 splits a GSO skb into N segments, it propagates N additional packets to its parent before returning NETXMITSUCCESS. The parent then accounts for the original skb once more, leaving its qlen one larger than the number of packets actually queued.

With QFQ as the parent, after all real packets are dequeued, QFQ still has a non-zero qlen while its in-service aggregate has no active classes. qfqchoosenextagg() returns NULL and qfqdequeue() passes the result to qfqpeekskb(), causing a NULL pointer dereference.

Follow the same pattern used by tbfsegment() and taprio: count only successfully queued segments, propagate the difference between the original skb and those segments, and return NETXMIT_SUCCESS whenever at least one segment was queued.