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From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Jakub Kicinski <jakub.kicinski@netronome.com>,
        Simon Horman <simon.horman@netronome.com>,
        "David S . Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>,
        netem@lists.linux-foundation.org, netdev@vger.kernel.org
Subject: [PATCH AUTOSEL 4.9 220/251] net: netem: correct the parent's backlog when corrupted packet was dropped
Date:   Thu, 16 Jan 2020 12:36:09 -0500
Message-Id: <20200116173641.22137-180-sashal@kernel.org>
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From: Jakub Kicinski <jakub.kicinski@netronome.com>

[ 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@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 11c4c93f5ded..e06491314d59 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -609,6 +609,8 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 		}
 		/* 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