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: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: sch_cake-avoid-possible-divide-by-zero-in-cake_enqueue.patch 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@xxxxxxxxxxxxxxx> know about it. >From foo@baz Sat 11 Jan 2020 09:14:34 AM CET From: Wen Yang <wenyang@xxxxxxxxxxxxxxxxx> Date: Thu, 2 Jan 2020 17:21:43 +0800 Subject: sch_cake: avoid possible divide by zero in cake_enqueue() From: Wen Yang <wenyang@xxxxxxxxxxxxxxxxx> [ 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@xxxxxxxxxxxxxxxxx> Cc: Kevin Darbyshire-Bryant <ldir@xxxxxxxxxxxxxxxxxxxxxxx> Cc: Toke Høiland-Jørgensen <toke@xxxxxxxxxx> Cc: David S. Miller <davem@xxxxxxxxxxxxx> Cc: Cong Wang <xiyou.wangcong@xxxxxxxxx> Cc: cake@xxxxxxxxxxxxxxxxxxxxx Cc: netdev@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Acked-by: Toke Høiland-Jørgensen <toke@xxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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); Patches currently in stable-queue which might be from wenyang@xxxxxxxxxxxxxxxxx are queue-4.19/sch_cake-avoid-possible-divide-by-zero-in-cake_enqueue.patch queue-4.19/regulator-fix-use-after-free-issue.patch