pkt_sched: Fix return value corruption in HTB and TBF.

Based upon a bug report by Josip Rodin.

Packet schedulers should only return NET_XMIT_DROP iff
the packet really was dropped.  If the packet does reach
the device after we return NET_XMIT_DROP then TCP can
crash because it depends upon the enqueue path return
values being accurate.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 9 deletions

diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index 7d3b7ff3bf0..94c61598b86 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -123,15 +123,8 @@ static int tbf_enqueue(struct sk_buff *skb, struct Qdisc* sch)
         struct tbf_sched_data *q = qdisc_priv(sch);
         int ret;
 
-        if (qdisc_pkt_len(skb) > q->max_size) {
-                sch->qstats.drops++;
-#ifdef CONFIG_NET_CLS_ACT
-                if (sch->reshape_fail == NULL || sch->reshape_fail(skb, sch))
-#endif
-                        kfree_skb(skb);
-
-                return NET_XMIT_DROP;
-        }
+        if (qdisc_pkt_len(skb) > q->max_size)
+                return qdisc_reshape_fail(skb, sch);
 
         ret = qdisc_enqueue(skb, q->qdisc);
         if (ret != 0) {