From: Simon Horman <horms@kernel.org>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: netdev@vger.kernel.org, jiri@resnulli.us, jhs@mojatatu.com,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Dave Taht <dave.taht@gmail.com>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net v8 6/6] net/sched: netem: check for negative latency and jitter
Date: Tue, 21 Apr 2026 14:16:33 +0100 [thread overview]
Message-ID: <20260421131633.GC651125@horms.kernel.org> (raw)
In-Reply-To: <20260418032027.900913-7-stephen@networkplumber.org>
On Fri, Apr 17, 2026 at 08:19:44PM -0700, Stephen Hemminger wrote:
> Reject requests with negative latency or jitter.
> A negative value added to current timestamp (u64) wraps
> to an enormous time_to_send, disabling dequeue.
> The original UAPI used u32 for these values; the conversion to 64-bit
> time values via TCA_NETEM_LATENCY64 and TCA_NETEM_JITTER64
> allowed signed values to reach the kernel without validation.
>
> Jitter is already silently clamped by an abs() in netem_change();
> that abs() can be removed in a follow-up once this rejection is in
> place.
>
> Fixes: 99803171ef04 ("netem: add uapi to express delay and jitter in nanoseconds")
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Reviewed-by: Simon Horman <horms@kernel.org>
next prev parent reply other threads:[~2026-04-21 13:16 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-18 3:19 [PATCH v8 net 0/6] netem: bug fixes Stephen Hemminger
2026-04-18 3:19 ` [PATCH net v8 1/6] net/sched: netem: fix probability gaps in 4-state loss model Stephen Hemminger
2026-04-18 3:19 ` [PATCH net v8 2/6] net/sched: netem: fix queue limit check to include reordered packets Stephen Hemminger
2026-04-21 13:15 ` Simon Horman
2026-04-18 3:19 ` [PATCH net v8 3/6] net/sched: netem: only reseed PRNG when seed is explicitly provided Stephen Hemminger
2026-04-18 3:19 ` [PATCH net v8 4/6] net/sched: netem: validate slot configuration Stephen Hemminger
2026-04-21 13:10 ` Simon Horman
2026-04-23 7:50 ` Paolo Abeni
2026-04-23 21:12 ` Jamal Hadi Salim
2026-04-24 15:07 ` Stephen Hemminger
2026-04-24 20:17 ` Jamal Hadi Salim
2026-04-24 23:06 ` Stephen Hemminger
2026-04-18 3:19 ` [PATCH net v8 5/6] net/sched: netem: fix slot delay calculation overflow Stephen Hemminger
2026-04-18 3:19 ` [PATCH net v8 6/6] net/sched: netem: check for negative latency and jitter Stephen Hemminger
2026-04-21 13:16 ` Simon Horman [this message]
2026-04-28 0:40 ` [PATCH v8 net 0/6] netem: bug fixes patchwork-bot+netdevbpf
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