[patch 23/42] pkt_sched: Fix return value corruption in HTB and TBF.

[Greg KH <gregkh@suse.de>]

[-- Attachment #1: 0004-pkt_sched-Fix-return-value-corruption-in-HTB-and-TB.patch --]
[-- Type: text/plain, Size: 2319 bytes --]

2.6.26-stable review patch.  If anyone has any objections, please let us know.

------------------

From: David S. Miller <davem@davemloft.net>

[ Upstream commit 69747650c814a8a79fef412c7416adf823293a3e ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 net/sched/sch_htb.c |   20 ++++++++++++--------
 net/sched/sch_tbf.c |   11 ++---------
 2 files changed, 14 insertions(+), 17 deletions(-)

--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -595,11 +595,13 @@ static int htb_enqueue(struct sk_buff *s
 		kfree_skb(skb);
 		return ret;
 #endif
-	} else if (cl->un.leaf.q->enqueue(skb, cl->un.leaf.q) !=
+	} else if ((ret = cl->un.leaf.q->enqueue(skb, cl->un.leaf.q)) !=
 		   NET_XMIT_SUCCESS) {
-		sch->qstats.drops++;
-		cl->qstats.drops++;
-		return NET_XMIT_DROP;
+		if (ret == NET_XMIT_DROP) {
+			sch->qstats.drops++;
+			cl->qstats.drops++;
+		}
+		return ret;
 	} else {
 		cl->bstats.packets +=
 			skb_is_gso(skb)?skb_shinfo(skb)->gso_segs:1;
@@ -639,11 +641,13 @@ static int htb_requeue(struct sk_buff *s
 		kfree_skb(skb);
 		return ret;
 #endif
-	} else if (cl->un.leaf.q->ops->requeue(skb, cl->un.leaf.q) !=
+	} else if ((ret = cl->un.leaf.q->ops->requeue(skb, cl->un.leaf.q)) !=
 		   NET_XMIT_SUCCESS) {
-		sch->qstats.drops++;
-		cl->qstats.drops++;
-		return NET_XMIT_DROP;
+		if (ret == NET_XMIT_DROP) {
+			sch->qstats.drops++;
+			cl->qstats.drops++;
+		}
+		return ret;
 	} else
 		htb_activate(q, cl);
 
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -123,15 +123,8 @@ static int tbf_enqueue(struct sk_buff *s
 	struct tbf_sched_data *q = qdisc_priv(sch);
 	int ret;
 
-	if (skb->len > 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 (skb->len > q->max_size)
+		return qdisc_reshape_fail(skb, sch);
 
 	if ((ret = q->qdisc->enqueue(skb, q->qdisc)) != 0) {
 		sch->qstats.drops++;

--