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From: Jakub Kicinski <kuba@kernel.org>
To: Eric Dumazet <edumazet@google.com>
Cc: Ke Li <keli@akamai.com>, netdev <netdev@vger.kernel.org>,
	David Miller <davem@davemloft.net>,
	kli@udel.edu, Ji Li <jli@akamai.com>
Subject: Re: [PATCH net v2] net: Properly typecast int values to set sk_max_pacing_rate
Date: Thu, 22 Oct 2020 12:25:34 -0700	[thread overview]
Message-ID: <20201022122534.5a700251@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net> (raw)
In-Reply-To: <CANn89iJxBMph1EZX9mYOjHsex-6thhTqSLpXA-1RDGv-QBhxaw@mail.gmail.com>

On Thu, 22 Oct 2020 09:48:48 +0200 Eric Dumazet wrote:
> On Thu, Oct 22, 2020 at 8:42 AM Ke Li <keli@akamai.com> wrote:
> >
> > In setsockopt(SO_MAX_PACING_RATE) on 64bit systems, sk_max_pacing_rate,
> > after extended from 'u32' to 'unsigned long', takes unintentionally
> > hiked value whenever assigned from an 'int' value with MSB=1, due to
> > binary sign extension in promoting s32 to u64, e.g. 0x80000000 becomes
> > 0xFFFFFFFF80000000.
> >
> > Thus inflated sk_max_pacing_rate causes subsequent getsockopt to return
> > ~0U unexpectedly. It may also result in increased pacing rate.
> >
> > Fix by explicitly casting the 'int' value to 'unsigned int' before
> > assigning it to sk_max_pacing_rate, for zero extension to happen.
> >
> > Fixes: 76a9ebe811fb ("net: extend sk_pacing_rate to unsigned long")
> > Signed-off-by: Ji Li <jli@akamai.com>
> > Signed-off-by: Ke Li <keli@akamai.com>
> > Cc: Eric Dumazet <edumazet@google.com>
> > ---
> > v2: wrap the line in net/core/filter.c to less than 80 chars.  
> 
> SGTM (the other version was also fine, the 80 chars rule has been
> relaxed/changed to 100 recently)

We went from old guidelines, to unclear guidelines, IDK which one is
worse :( Here the way the ternary expression was wrapping in a 80 char
window looked way less readable, so I thought I'd request a reformat.

> Reviewed-by: Eric Dumazet <edumazet@google.com>

Applied, thanks everyone!

      parent reply	other threads:[~2020-10-22 19:25 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-22  6:41 [PATCH net v2] net: Properly typecast int values to set sk_max_pacing_rate Ke Li
2020-10-22  7:48 ` Eric Dumazet
2020-10-22  8:43   ` Li, Ke
2020-10-22 14:19     ` Eric Dumazet
2020-10-22 17:45       ` Li, Ke
2020-10-22 19:25   ` Jakub Kicinski [this message]

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