[PATCH net v2 00/10] netem: fixes and selftests

[Stephen Hemminger <stephen@networkplumber.org>]

The check_netem_in_tree() restriction added for CVE-2024-45016 rejects
valid configurations such as HTB or HFSC trees with netem on multiple
branches -- including examples from the netem documentation itself.
This has been an open issue for over a year (kernel.org bug #220774).

This series replaces it with a per-CPU recursion guard, restructures
dequeue to fix the HFSC eltree corruption, and addresses several
additional bugs found during a code audit.

  01/10  Revert check_netem_in_tree()
  02/10  Per-CPU recursion guard for duplication
  03/10  Update tdc tests for the revert
  04/10  Restructure dequeue to fix HFSC re-entrancy
         (CVE-2025-37890, CVE-2025-38001)
  05/10  Fix probability gaps in 4-state loss model
  06/10  Fix slot delay overflow for ranges > 2.1s
  07/10  Include reordered packets in queue limit check
  08/10  Null-terminate tfifo linear queue tail
  09/10  Only reseed PRNG when explicitly provided
  10/10  Add netem configuration and traffic tests

Tested with tdc on 7.0.0-rc3: all netem tests pass.

v2 - merge new tests into tc-testing
   - fixes only in this patch series

Stephen Hemminger (10):
  Revert "net/sched: Restrict conditions for adding duplicating netems
    to qdisc tree"
  net/sched: netem: add per-CPU recursion guard for duplication
  selftests/tc-testing: update netem tests after check_netem_in_tree
    revert
  net/sched: netem: restructure dequeue to avoid re-entrancy with child
    qdisc
  net/sched: netem: fix probability gaps in 4-state loss model
  net/sched: netem: fix slot delay calculation overflow
  net/sched: netem: fix queue limit check to include reordered packets
  net/sched: netem: null-terminate tfifo linear queue tail
  net/sched: netem: only reseed PRNG when seed is explicitly provided
  selftests/tc-testing: add netem configuration and traffic tests

 net/sched/sch_netem.c                         | 164 ++---
 .../tc-testing/tc-tests/qdiscs/netem.json     | 610 +++++++++++++++++-
 2 files changed, 689 insertions(+), 85 deletions(-)

-- 
2.51.0