[PATCH 4.9 218/271] net: netem: correct the parents backlog when corrupted packet was dropped

From: Greg Kroah-Hartman
Date: Tue Jan 28 2020 - 09:24:00 EST


From: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx>

[ Upstream commit e0ad032e144731a5928f2d75e91c2064ba1a764c ]

If packet corruption failed we jump to finish_segs and return
NET_XMIT_SUCCESS. Seeing success will make the parent qdisc
increment its backlog, that's incorrect - we need to return
NET_XMIT_DROP.

Fixes: 6071bd1aa13e ("netem: Segment GSO packets on enqueue")
Signed-off-by: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx>
Reviewed-by: Simon Horman <simon.horman@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/sched/sch_netem.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 11c4c93f5ded7..e06491314d592 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -609,6 +609,8 @@ finish_segs:
}
/* Parent qdiscs accounted for 1 skb of size @prev_len */
qdisc_tree_reduce_backlog(sch, -(nb - 1), -(len - prev_len));
+ } else if (!skb) {
+ return NET_XMIT_DROP;
}
return NET_XMIT_SUCCESS;
}
--
2.20.1