From: Eric Dumazet <edumazet@google.com>
To: Ke Li <keli@akamai.com>
Cc: netdev <netdev@vger.kernel.org>,
David Miller <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
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 09:48:48 +0200 [thread overview]
Message-ID: <CANn89iJxBMph1EZX9mYOjHsex-6thhTqSLpXA-1RDGv-QBhxaw@mail.gmail.com> (raw)
In-Reply-To: <20201022064146.79873-1-keli@akamai.com>
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)
Reviewed-by: Eric Dumazet <edumazet@google.com>
next prev parent reply other threads:[~2020-10-22 7:49 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 [this message]
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
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