tipc: refactor node xmit and fix memory leaks

Refactor tipc_node_xmit() to fail fast and fail early. Fix several
potential memory leaks in unexpected error paths.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Richard Alpe <richard.alpe@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 38 insertions, 24 deletions

diff --git a/net/tipc/link.c b/net/tipc/link.c
index 6f4a6d9b0149..3e513daecf80 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -903,8 +903,10 @@ int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
                 if (unlikely(l->backlog[i].len >= l->backlog[i].limit))
                         return link_schedule_user(l, list);
         }
-        if (unlikely(msg_size(hdr) > mtu))
+        if (unlikely(msg_size(hdr) > mtu)) {
+                skb_queue_purge(list);
                 return -EMSGSIZE;
+        }
 
         /* Prepare each packet for sending, and add to relevant queue: */
         while (skb_queue_len(list)) {
@@ -916,8 +918,10 @@ int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
 
                 if (likely(skb_queue_len(transmq) < maxwin)) {
                         _skb = skb_clone(skb, GFP_ATOMIC);
-                        if (!_skb)
+                        if (!_skb) {
+                                skb_queue_purge(list);
                                 return -ENOBUFS;
+                        }
                         __skb_dequeue(list);
                         __skb_queue_tail(transmq, skb);
                         __skb_queue_tail(xmitq, _skb);
diff --git a/net/tipc/node.c b/net/tipc/node.c
index f8a8255a7182..10a1e8717c6f 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -1166,7 +1166,7 @@ msg_full:
  * @dnode: address of destination node
  * @selector: a number used for deterministic link selection
  * Consumes the buffer chain, except when returning -ELINKCONG
- * Returns 0 if success, otherwise errno: -ELINKCONG,-EHOSTUNREACH,-EMSGSIZE
+ * Returns 0 if success, otherwise: -ELINKCONG,-EHOSTUNREACH,-EMSGSIZE,-ENOBUF
  */
 int tipc_node_xmit(struct net *net, struct sk_buff_head *list,
                    u32 dnode, int selector)
@@ -1174,33 +1174,43 @@ int tipc_node_xmit(struct net *net, struct sk_buff_head *list,
         struct tipc_link_entry *le = NULL;
         struct tipc_node *n;
         struct sk_buff_head xmitq;
-        int bearer_id = -1;
-        int rc = -EHOSTUNREACH;
+        int bearer_id;
+        int rc;
+
+        if (in_own_node(net, dnode)) {
+                tipc_sk_rcv(net, list);
+                return 0;
+        }
 
-        __skb_queue_head_init(&xmitq);
         n = tipc_node_find(net, dnode);
-        if (likely(n)) {
-                tipc_node_read_lock(n);
-                bearer_id = n->active_links[selector & 1];
-                if (bearer_id >= 0) {
-                        le = &n->links[bearer_id];
-                        spin_lock_bh(&le->lock);
-                        rc = tipc_link_xmit(le->link, list, &xmitq);
-                        spin_unlock_bh(&le->lock);
-                }
+        if (unlikely(!n)) {
+                skb_queue_purge(list);
+                return -EHOSTUNREACH;
+        }
+
+        tipc_node_read_lock(n);
+        bearer_id = n->active_links[selector & 1];
+        if (unlikely(bearer_id == INVALID_BEARER_ID)) {
                 tipc_node_read_unlock(n);
-                if (likely(!rc))
-                        tipc_bearer_xmit(net, bearer_id, &xmitq, &le->maddr);
-                else if (rc == -ENOBUFS)
-                        tipc_node_link_down(n, bearer_id, false);
                 tipc_node_put(n);
-                return rc;
+                skb_queue_purge(list);
+                return -EHOSTUNREACH;
         }
 
-        if (likely(in_own_node(net, dnode))) {
-                tipc_sk_rcv(net, list);
-                return 0;
-        }
+        __skb_queue_head_init(&xmitq);
+        le = &n->links[bearer_id];
+        spin_lock_bh(&le->lock);
+        rc = tipc_link_xmit(le->link, list, &xmitq);
+        spin_unlock_bh(&le->lock);
+        tipc_node_read_unlock(n);
+
+        if (likely(rc == 0))
+                tipc_bearer_xmit(net, bearer_id, &xmitq, &le->maddr);
+        else if (rc == -ENOBUFS)
+                tipc_node_link_down(n, bearer_id, false);
+
+        tipc_node_put(n);
+
         return rc;
 }