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>

2 files changed, 4 insertions, 11 deletions

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 6febd245e62b..0df0df202ed0 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -577,7 +577,7 @@ static int htb_enqueue(struct sk_buff *skb, struct Qdisc *sch)
                         sch->qstats.drops++;
                         cl->qstats.drops++;
                 }
-                return NET_XMIT_DROP;
+                return ret;
         } else {
                 cl->bstats.packets +=
                         skb_is_gso(skb)?skb_shinfo(skb)->gso_segs:1;
@@ -623,7 +623,7 @@ static int htb_requeue(struct sk_buff *skb, struct Qdisc *sch)
                         sch->qstats.drops++;
                         cl->qstats.drops++;
                 }
-                return NET_XMIT_DROP;
+                return ret;
         } else
                 htb_activate(q, cl);
 
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index 7d3b7ff3bf07..94c61598b86a 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) {