[PATCH v7 0/5] netem: bug fixes

Stephen Hemminger
2026-04-15T14:28:26Z

These bugs were found when doing AI assisted review of sch_netem.c
during investigation of the packet duplication recursion problem
addressed in Jamal's series.

The fixes cover:

- probability gaps in the 4-state Markov loss model
- queue limit not accounting for reordered packets
- PRNG reseeded on every tc change, breaking reproducibility
- slot delay configuration not validated for inverted ranges
- slot delay arithmetic overflow for ranges above ~2.1 seconds

v7 - queue limit check Fixes: goes back further to earlier change
- use NL_SET_ERR_MSG_ATTR

Stephen Hemminger (5):
net/sched: netem: fix probability gaps in 4-state loss model
net/sched: netem: fix queue limit check to include reordered packets
net/sched: netem: only reseed PRNG when seed is explicitly provided
net/sched: netem: check for invalid slot range
net/sched: netem: fix slot delay calculation overflow

net/sched/sch_netem.c | 44 +++++++++++++++++++++++++++++++------------
1 file changed, 32 insertions(+), 12 deletions(-)

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2.53.0