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

@@ -407,9 +407,7 @@ int tipc_bclink_send_msg(struct sk_buff *buf)
 	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

@@ -864,8 +864,9 @@ int tipc_link_send_buf(struct link *l_ptr, struct sk_buff *buf)
 
 	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 @@ int tipc_link_send_sections_fast(struct tipc_port *sender,
 			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);