netdev - Re: [PATCH] sch_cake: avoid possible divide by zero in cake

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Message-ID: <87ftgxl9g6.fsf@toke.dk>
Date:   Fri, 03 Jan 2020 00:34:01 +0100
From:   Toke Høiland-Jørgensen <toke@...e.dk>
To:     Wen Yang <wenyang@...ux.alibaba.com>
Cc:     Wen Yang <wenyang@...ux.alibaba.com>,
        Kevin Darbyshire-Bryant <ldir@...byshire-bryant.me.uk>,
        "David S . Miller" <davem@...emloft.net>,
        Cong Wang <xiyou.wangcong@...il.com>,
        cake@...ts.bufferbloat.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sch_cake: avoid possible divide by zero in cake_enqueue()

Wen Yang <wenyang@...ux.alibaba.com> writes:

> The variables 'window_interval' is u64 and do_div()
> truncates it to 32 bits, which means it can test
> non-zero and be truncated to zero for division.
> The unit of window_interval is nanoseconds,
> so its lower 32-bit is relatively easy to exceed.
> Fix this issue by using div64_u64() instead.
>
> Fixes: 7298de9cd725 ("sch_cake: Add ingress mode")
> Signed-off-by: Wen Yang <wenyang@...ux.alibaba.com>
> Cc: Kevin Darbyshire-Bryant <ldir@...byshire-bryant.me.uk>
> Cc: Toke Høiland-Jørgensen <toke@...hat.com>
> Cc: David S. Miller <davem@...emloft.net>
> Cc: Cong Wang <xiyou.wangcong@...il.com>
> Cc: cake@...ts.bufferbloat.net
> Cc: netdev@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org

Acked-by: Toke Høiland-Jørgensen <toke@...e.dk>