netdev - [net 1/2] Revert "tipc: Fix potential tipc_node refcnt leak in tipc

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Message-Id: <20200602044641.10535-2-tuong.t.lien@dektech.com.au>
Date:   Tue,  2 Jun 2020 11:46:40 +0700
From:   Tuong Lien <tuong.t.lien@...tech.com.au>
To:     davem@...emloft.net, jmaloy@...hat.com, maloy@...jonn.com,
        ying.xue@...driver.com, netdev@...r.kernel.org
Cc:     tipc-discussion@...ts.sourceforge.net
Subject: [net 1/2] Revert "tipc: Fix potential tipc_node refcnt leak in tipc_rcv"

This reverts commit de058420767df21e2b6b0f3bb36d1616fb962032.

There is no actual tipc_node refcnt leak as stated in the above commit.
The refcnt is hold carefully for the case of an asynchronous decryption
(i.e. -EINPROGRESS/-EBUSY and skb = NULL is returned), so that the node
object cannot be freed in the meantime. The counter will be re-balanced
when the operation's callback arrives with the decrypted buffer if any.
In other cases, e.g. a synchronous crypto the counter will be decreased
immediately when it is done.

Now with that commit, a kernel panic will occur when there is no node
found (i.e. n = NULL) in the 'tipc_rcv()' or a premature release of the
node object.

This commit solves the issues by reverting the said commit, but keeping
one valid case that the 'skb_linearize()' is failed.

Acked-by: Jon Maloy <jmaloy@...hat.com>
Signed-off-by: Tuong Lien <tuong.t.lien@...tech.com.au>
---
 net/tipc/node.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/net/tipc/node.c b/net/tipc/node.c
index 0312fb181d94..a4c2816c3746 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -2038,7 +2038,6 @@ 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;

-- 
2.13.7