In the Linux kernel, the following vulnerability has been resolved:
net/sched: sch_qfq: Fix race condition on qfq_aggregate
A race condition can occur when 'agg' is modified in qfq_change_agg (called during qfq_enqueue) while other threads access it concurrently. For example, qfq_dump_class may trigger a NULL dereference, and qfq_delete_class may cause a use-after-free.
This patch addresses the issue by:
Moved qfq_destroy_class into the critical section.
Added sch_tree_lock protection to qfq_dump_class and qfq_dump_class_stats.