CVE-2025-40083 net/sched: sch_qfq: Fix null-deref in agg_dequeue

In the Linux kernel, the following vulnerability has been resolved: net/sched: schqfq: Fix null-deref in aggdequeue To prevent a potential crash in aggdequeue net/sched/schqfq.c when cl-qdisc-ops-peekcl-qdisc returns NULL, we check the return value before using it, similar to the existing approac...