CVE-2026-52997— Linux kernel 安全漏洞

net/sched: sch_dualpi2: drain both C-queue and L-queue in dualpi2_change()

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

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Linux kernel 安全漏洞

Linux kernel是美国Linux基金会开源的操作系统Linux所使用的内核。 Linux kernel 6.17版本存在安全漏洞，该漏洞源于dualpi2_change函数在执行限制或内存限制时未正确处理C队列和L队列的出队操作，可能导致空指针取消引用。

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