[Cake] Patch "sch_cake: avoid possible divide by zero in cake_enqueue()" has been added to the 4.19-stable tree

gregkh at linuxfoundation.org gregkh at linuxfoundation.org
Sat Jan 11 03:18:04 EST 2020

This is a note to let you know that I've just added the patch titled

    sch_cake: avoid possible divide by zero in cake_enqueue()

to the 4.19-stable tree which can be found at:

The filename of the patch is:
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.

>From foo at baz Sat 11 Jan 2020 09:14:34 AM CET
From: Wen Yang <wenyang at linux.alibaba.com>
Date: Thu, 2 Jan 2020 17:21:43 +0800
Subject: sch_cake: avoid possible divide by zero in cake_enqueue()

From: Wen Yang <wenyang at 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 at linux.alibaba.com>
Cc: Kevin Darbyshire-Bryant <ldir at darbyshire-bryant.me.uk>
Cc: Toke Høiland-Jørgensen <toke at redhat.com>
Cc: David S. Miller <davem at davemloft.net>
Cc: Cong Wang <xiyou.wangcong at gmail.com>
Cc: cake at lists.bufferbloat.net
Cc: netdev at vger.kernel.org
Cc: linux-kernel at vger.kernel.org
Acked-by: Toke Høiland-Jørgensen <toke at toke.dk>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh at 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 *
 			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);

Patches currently in stable-queue which might be from wenyang at linux.alibaba.com are


More information about the Cake mailing list