tipc: Fix sk_buff leaks when link congestion is detected

Modifies a TIPC send routine that did not discard the outgoing sk_buff
if it was not transmitted because of link congestion; this eliminates
the potential for buffer leakage in the many callers who did not clean up
the unsent buffer. (The two routines that previously did discard the unsent
buffer have been updated to eliminate their now-redundant clean up.)

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

net/tipc/bcast.c

diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c
index 08e3216..fa68d1e 100644
--- a/net/tipc/bcast.c
+++ b/net/tipc/bcast.c
@@ -407,9 +407,7 @@
 	spin_lock_bh(&bc_lock);
 
 	res = tipc_link_send_buf(bcl, buf);
-	if (unlikely(res == -ELINKCONG))
-		buf_discard(buf);
-	else
+	if (likely(res > 0))
 		bclink_set_last_sent();
 
 	bcl->stats.queue_sz_counts++;

net/tipc/link.c

diff --git a/net/tipc/link.c b/net/tipc/link.c
index 02b083e..2a9f44a 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -864,8 +864,9 @@
 
 	if (unlikely(queue_size >= queue_limit)) {
 		if (imp <= TIPC_CRITICAL_IMPORTANCE) {
-			return link_schedule_port(l_ptr, msg_origport(msg),
-						  size);
+			link_schedule_port(l_ptr, msg_origport(msg), size);
+			buf_discard(buf);
+			return -ELINKCONG;
 		}
 		buf_discard(buf);
 		if (imp > CONN_MANAGER) {
@@ -1069,8 +1070,6 @@
 			if (likely(buf)) {
 				res = link_send_buf_fast(l_ptr, buf,
 							 &sender->max_pkt);
-				if (unlikely(res < 0))
-					buf_discard(buf);
 exit:
 				tipc_node_unlock(node);
 				read_unlock_bh(&tipc_net_lock);