* [Cake] [PATCH 4.19 73/84] sch_cake: avoid possible divide by zero in cake_enqueue()
[not found] <20200111094845.328046411@linuxfoundation.org>
@ 2020-01-11 9:50 ` Greg Kroah-Hartman
0 siblings, 0 replies; only message in thread
From: Greg Kroah-Hartman @ 2020-01-11 9:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Wen Yang, Kevin Darbyshire-Bryant,
Toke Høiland-Jørgensen, David S. Miller, Cong Wang,
cake, netdev, Toke Høiland-Jørgensen
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);
^ permalink raw reply [flat|nested] only message in thread