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From: Bui Viet Dung <dungvn2345@gmail.com>
To: netdev-bot+sashiko@kernel.org
Cc: stephen@networkplumber.org, jhs@mojatatu.com, jiri@resnulli.us,
	davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org,
	pabeni@redhat.com, horms@kernel.org, hagen@jauu.net,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH net v2] net/sched: sch_netem: prevent packet length underflow with negative overhead
Date: Tue, 13 Oct 2026 07:16:28 -0700 (PDT)	[thread overview]
Message-ID: <6ace3d3c.c6d97709.27aae3.cbd7@mx.google.com> (raw)
In-Reply-To: <179186709813.434549.16042014331752584322@kernel.org>

Hi,

Thanks for the detailed review. Both points are valid and critical:

1. mul_u64_u64_div_u64() on x86-64 uses 'divq' without overflow handling,
   which raises a #DE divide exception when (len * NSEC_PER_SEC) / rate
   overflows u64.
2. Returning S64_MAX can overflow the subsequent 'now + delay' addition in
   netem_enqueue().

I will retract v2 and prepare a proper v3.

pw-bot: cr

      reply	other threads:[~2026-10-13 14:16 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-12  4:43 [PATCH net v2] net/sched: sch_netem: prevent packet length underflow with negative overhead Bui Viet Dung
2026-10-12  9:28 ` [syzbot ci] " syzbot ci
2026-10-13  4:51 ` [PATCH net v2] " netdev-bot+sashiko
2026-10-13 14:16   ` Bui Viet Dung [this message]

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