| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.19 73/84] sch_cake: avoid possible divide by zero in cake_enqueue() | Date | Sat, 11 Jan 2020 10:50:50 +0100 |
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From: Wen Yang <wenyang@linux.alibaba.com>
[ Upstream commit 68aab823c223646fab311f8a6581994facee66a0 ]
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@linux.alibaba.com> Cc: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk> Cc: Toke Høiland-Jørgensen <toke@redhat.com> Cc: David S. Miller <davem@davemloft.net> Cc: Cong Wang <xiyou.wangcong@gmail.com> Cc: cake@lists.bufferbloat.net Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Acked-by: Toke Høiland-Jørgensen <toke@toke.dk> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/sched/sch_cake.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/sched/sch_cake.c +++ b/net/sched/sch_cake.c @@ -1758,7 +1758,7 @@ static s32 cake_enqueue(struct sk_buff * q->avg_window_begin)); u64 b = q->avg_window_bytes * (u64)NSEC_PER_SEC; - do_div(b, window_interval); + b = div64_u64(b, window_interval); q->avg_peak_bandwidth = cake_ewma(q->avg_peak_bandwidth, b, b > q->avg_peak_bandwidth ? 2 : 8);
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