CVE-2026-52997

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net/sched: sch_dualpi2: drain both C-queue and L-queue in dualpi2_change()<br /> <br /> Fix dualpi2_change() to correctly enforce updated limit and memlimit<br /> values after a configuration change of the dualpi2 qdisc.<br /> <br /> Before this patch, dualpi2_change() always attempted to dequeue packets<br /> via the root qdisc (C-queue) when reducing backlog or memory usage, and<br /> unconditionally assumed that a valid skb will be returned. When traffic<br /> classification results in packets being queued in the L-queue while the<br /> C-queue is empty, this leads to a NULL skb dereference during limit or<br /> memlimit enforcement.<br /> <br /> This is fixed by first dequeuing from the C-queue path if it is<br /> non-empty. Once the C-queue is empty, packets are dequeued directly from<br /> the L-queue. Return values from qdisc_dequeue_internal() are checked for<br /> both queues. When dequeuing from the L-queue, the parent qdisc qlen and<br /> backlog counters are updated explicitly to keep overall qdisc statistics<br /> consistent.