From de058420767df21e2b6b0f3bb36d1616fb962032 Mon Sep 17 00:00:00 2001
From: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Date: Wed, 15 Apr 2020 16:40:28 +0800
Subject: tipc: Fix potential tipc_node refcnt leak in tipc_rcv

tipc_rcv() invokes tipc_node_find() twice, which returns a reference of
the specified tipc_node object to "n" with increased refcnt.

When tipc_rcv() returns or a new object is assigned to "n", the original
local reference of "n" becomes invalid, so the refcount should be
decreased to keep refcount balanced.

The issue happens in some paths of tipc_rcv(), which forget to decrease
the refcnt increased by tipc_node_find() and will cause a refcnt leak.

Fix this issue by calling tipc_node_put() before the original object
pointed by "n" becomes invalid.

Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/tipc/node.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

(limited to 'net/tipc/node.c')

diff --git a/net/tipc/node.c b/net/tipc/node.c
index 10292c942384..803a3a6d0f50 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -2038,6 +2038,7 @@ void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b)
 		n = tipc_node_find_by_id(net, ehdr->id);
 	}
 	tipc_crypto_rcv(net, (n) ? n->crypto_rx : NULL, &skb, b);
+	tipc_node_put(n);
 	if (!skb)
 		return;
 
@@ -2090,7 +2091,7 @@ rcv:
 	/* Check/update node state before receiving */
 	if (unlikely(skb)) {
 		if (unlikely(skb_linearize(skb)))
-			goto discard;
+			goto out_node_put;
 		tipc_node_write_lock(n);
 		if (tipc_node_check_state(n, skb, bearer_id, &xmitq)) {
 			if (le->link) {
@@ -2119,6 +2120,7 @@ rcv:
 	if (!skb_queue_empty(&xmitq))
 		tipc_bearer_xmit(net, bearer_id, &xmitq, &le->maddr, n);
 
+out_node_put:
 	tipc_node_put(n);
 discard:
 	kfree_skb(skb);
-- 
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