netdev - [PATCH net 0/3] net/sched: teql: Enforce hierarchy placement

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Message-Id: <20260114160243.913069-1-jhs@mojatatu.com>
Date: Wed, 14 Jan 2026 11:02:40 -0500
From: Jamal Hadi Salim <jhs@...atatu.com>
To: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	horms@...nel.org,
	andrew+netdev@...n.ch
Cc: netdev@...r.kernel.org,
	xiyou.wangcong@...il.com,
	jiri@...nulli.us,
	victor@...atatu.com,
	km.kim1503@...il.com,
	security@...nel.org,
	Jamal Hadi Salim <jhs@...atatu.com>
Subject: [PATCH net 0/3] net/sched: teql: Enforce hierarchy placement

GangMin Kim <km.kim1503@...il.com> managed to create a UAF on qfq by inserting
teql as a child qdisc and exploiting a qlen sync issue.
teql is not intended to be used as a child qdisc. Lets enforce that rule in
patch #1. Although patch #1 fixes the issue, we prevent another potential qlen
exploit in qfq in patch #2 by enforcing the child's active status is not
determined by inspecting the qlen. In patch #3 we add a tdc test case.


Jamal Hadi Salim (2):
  net/sched: Enforce that teql can only be used as root qdisc
  net/sched: qfq: Use cl_is_active to determine whether  class is active
    in qfq_rm_from_ag

Victor Nogueira (1):
  selftests/tc-testing: Try to add teql as a child qdisc

 net/sched/sch_qfq.c                           |  2 +-
 net/sched/sch_teql.c                          |  5 ++++
 .../tc-testing/tc-tests/qdiscs/teql.json      | 25 +++++++++++++++++++
 3 files changed, 31 insertions(+), 1 deletion(-)

-- 
2.34.1