CVE-2024-56770

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description The issue is related to the Linux kernel's netem qdisc, which fails to account for backlog updates from child qdiscs. Specifically, the qlen value of netem only accounts for packets in its internal tfifo, but not for packets held by its children. When a child qdisc creates new packets during enqueue and informs netem about this, netem's qlen value is increased, but not updated when netem dequeues these packets. This can cause the qlen value to reach the configured limit, stopping the enqueue function even though the tfifo is not full. The problem can be reproduced by configuring netem as the root qdisc and tbf as its child, and sending bulk TCP traffic. The issue has been fixed by adding a counter for tfifo entries, ensuring that qlen is only decreased when a packet is returned by the dequeue function.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.