CVE-2025-39766

Description

In the Linux kernel, the following vulnerability has been resolved:net/sched: Make cake_enqueue return NET_XMIT_CN when past buffer_limitThe following setup can trigger a WARNING in htb_activate due tothe condition: !cl->leaf.q->q.qlentc qdisc del dev lo roottc qdisc add dev lo root handle 1: htb default 1tc class add dev lo parent 1: classid 1:1 htb rate 64bittc qdisc add dev lo parent 1:1 handle f: cake memlimit 1bping -I lo -f -c1 -s64 -W0.001 127.0.0.1This is because the low memlimit leads to a low buffer_limit, whichcauses packet dropping. However, cake_enqueue still returnsNET_XMIT_SUCCESS, causing htb_enqueue to call htb_activate with anempty child qdisc. We should return NET_XMIT_CN when packets aredropped from the same tin and flow.I do not believe return value of NET_XMIT_CN is necessary for packetdrops in the case of ack filtering, as that is meant to optimizeperformance, not to signal congestion.

Risk Information

Associated Vulnerability

Patch Details

References

https://nvd.nist.gov/vuln/detail/CVE-2023-1234
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-1234