From: Jiayuan Chen <jiayuan.chen@linux.dev>
To: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org, Eric Dumazet <edumazet@kernel.org>,
Eric Dumazet <edumazet@google.com>,
Neal Cardwell <ncardwell@google.com>,
Kuniyuki Iwashima <kuniyu@google.com>,
"David S. Miller" <davem@davemloft.net>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
Stephen Hemminger <stephen@networkplumber.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next v2 3/3] tcp_cubic: fix divide by zero and endless loop on bad module params
Date: Wed, 7 Oct 2026 11:55:48 +0800 [thread overview]
Message-ID: <8a8241c4-0e41-4ddd-aeef-b9ecb4f55d3a@linux.dev> (raw)
In-Reply-To: <20261005171227.2014f26e@kernel.org>
On 10/6/26 8:12 AM, Jakub Kicinski wrote:
> On Thu, 1 Oct 2026 19:29:43 +0800 Jiayuan Chen wrote:
>> Subject: [PATCH net-next v2 3/3] tcp_cubic: fix divide by zero and endless loop on bad module params
> if the LLM Medium severity complaint is true maybe also update
> the subject? I thought there's an actual div by zero somewhere
> but the commit msg seems to describe the inf loop
Hi Kuba, sorry for the delay.
The LLM is talking about (cwnd * beta_scale) wrapping, which needs
cwnd >= 33M packets, way past the 1M limit this code documents. So
the loop fix is fine.
The div by zero is real: beta == 1024 in "/ (BICTCP_BETA_SCALE - beta)"
and bic_scale == 0 in do_div(), both at init. The new range check in
this patch rejects both, I just did not say "divide by zero" in the
commit message.
Want me to spell this out in the commit message? I can also add the
READ_ONCE() Eric mentioned in the same respin.
next prev parent reply other threads:[~2026-10-07 6:49 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-01 11:29 [PATCH net-next v2 0/3] tcp: fix a few divide-by-zero in congestion control modules Jiayuan Chen
2026-10-01 11:29 ` [PATCH net-next v2 1/3] tcp_bic: fix divide by zero on max_increment == 0 Jiayuan Chen
2026-10-01 11:29 ` [PATCH net-next v2 2/3] tcp_hybla: fix divide by zero on rtt0 " Jiayuan Chen
2026-10-02 11:32 ` netdev-bot+sashiko
2026-10-01 11:29 ` [PATCH net-next v2 3/3] tcp_cubic: fix divide by zero and endless loop on bad module params Jiayuan Chen
2026-10-01 15:37 ` Eric Dumazet
2026-10-02 11:32 ` netdev-bot+sashiko
2026-10-06 0:12 ` Jakub Kicinski
2026-10-07 3:55 ` Jiayuan Chen [this message]
2026-10-07 13:24 ` Neal Cardwell
2026-10-01 11:33 ` [PATCH net-next v2 0/3] tcp: fix a few divide-by-zero in congestion control modules netdev-bot+sinfo
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