netdev - Re: [PATCH net 2/4] tcp: tcp_fragment() should apply sane memory limits

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Date:   Thu, 11 Jul 2019 20:50:13 +0200
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Michal Kubecek <mkubecek@...e.cz>, netdev@...r.kernel.org
Cc:     Eric Dumazet <eric.dumazet@...il.com>,
        Christoph Paasch <christoph.paasch@...il.com>,
        "Prout, Andrew - LLSC - MITLL" <aprout@...mit.edu>,
        David Miller <davem@...emloft.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jonathan Looney <jtl@...flix.com>,
        Neal Cardwell <ncardwell@...gle.com>,
        Tyler Hicks <tyhicks@...onical.com>,
        Yuchung Cheng <ycheng@...gle.com>,
        Bruce Curtis <brucec@...flix.com>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Dustin Marquess <dmarquess@...le.com>
Subject: Re: [PATCH net 2/4] tcp: tcp_fragment() should apply sane memory
 limits



On 7/11/19 8:26 PM, Michal Kubecek wrote:

> 
> I'm aware it's not a realistic test. It was written as quick and simple
> check of the pre-4.19 patch, but it shows that even TLP may not get
> through.


Most of TLP probes send new data, not rtx.

But yes, I get your point.

SO_SNDBUF=15000 in your case is seriously wrong.

Lets code a safety feature over SO_SNDBUF to not allow pathological small values,
because I do not want to support a constrained TCP stack in 2019.