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

[Pedro Tammela <pctammela@mojatatu.com>]

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/


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 |  1 +
 include/net/tc_class.h    | 33 +++++++++++++++++++++++++++++++++
 net/sched/sch_drr.c       | 12 +++++++-----
 net/sched/sch_hfsc.c      | 11 +++++++----
 net/sched/sch_htb.c       | 11 ++++++-----
 net/sched/sch_qfq.c       | 11 ++++++-----
 6 files changed, 60 insertions(+), 19 deletions(-)
 create mode 100644 include/net/tc_class.h

-- 
2.39.2