netdev - [PATCH net-next v2 0/5] net/sched: improve class lifetime handling

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Message-Id: <20230728153537.1865379-1-pctammela@mojatatu.com>
Date: Fri, 28 Jul 2023 12:35:32 -0300
From: Pedro Tammela <pctammela@...atatu.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	jhs@...atatu.com,
	xiyou.wangcong@...il.com,
	jiri@...nulli.us,
	Pedro Tammela <pctammela@...atatu.com>
Subject: [PATCH net-next v2 0/5] net/sched: improve class lifetime handling

Valis says[0]:
============
Three classifiers (cls_fw, cls_u32 and cls_route) always copy
tcf_result struct into the new instance of the filter on update.

This causes a problem when updating a filter bound to a class,
as tcf_unbind_filter() is always called on the old instance in the
success path, decreasing filter_cnt of the still referenced class
and allowing it to be deleted, leading to a use-after-free.
============

Turns out these could have been spotted easily with proper warnings.
Improve the current class lifetime with wrappers that check for
overflow/underflow.

While at it add an extack for when a class in use is deleted.

[0] https://lore.kernel.org/all/20230721174856.3045-1-sec@valis.email/

v1 -> v2:
   - Add ack tag from Jamal
   - Move definitions to sch_generic.h as suggested by Cong

Pedro Tammela (5):
  net/sched: wrap open coded Qdics class filter counter
  net/sched: sch_drr: warn about class in use while deleting
  net/sched: sch_hfsc: warn about class in use while deleting
  net/sched: sch_htb: warn about class in use while deleting
  net/sched: sch_qfq: warn about class in use while deleting

 include/net/sch_generic.h | 26 ++++++++++++++++++++++++++
 net/sched/sch_drr.c       | 11 ++++++-----
 net/sched/sch_hfsc.c      | 10 ++++++----
 net/sched/sch_htb.c       | 10 +++++-----
 net/sched/sch_qfq.c       | 12 ++++++------
 5 files changed, 49 insertions(+), 20 deletions(-)

-- 
2.39.2