[PATCH 4.17 201/324] tipc: fix wrong return value from function tipc_node_try_addr()

[Greg Kroah-Hartman]

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jon Maloy <jon.maloy@xxxxxxxxxxxx>

[ Upstream commit 2a57f182420174c7fd4b19db979a2d135231a963 ]

The function for checking if there is an node address conflict is
supposed to return a suggestion for a new address if it finds a
conflict, and zero otherwise. But in case the peer being checked
is previously unknown it does instead return a "suggestion" for
the checked address itself. This results in a DSC_TRIAL_FAIL_MSG
being sent unecessarily to the peer, and sometimes makes the trial
period starting over again.

Fixes: 25b0b9c4e835 ("tipc: handle collisions of 32-bit node address hash values")
Signed-off-by: Jon Maloy <jon.maloy@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/tipc/node.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -776,6 +776,7 @@ static u32 tipc_node_suggest_addr(struct
 }
 
 /* tipc_node_try_addr(): Check if addr can be used by peer, suggest other if not
+ * Returns suggested address if any, otherwise 0
  */
 u32 tipc_node_try_addr(struct net *net, u8 *id, u32 addr)
 {
@@ -798,12 +799,14 @@ u32 tipc_node_try_addr(struct net *net,
 	if (n) {
 		addr = n->addr;
 		tipc_node_put(n);
+		return addr;
 	}
-	/* Even this node may be in trial phase */
+
+	/* Even this node may be in conflict */
 	if (tn->trial_addr == addr)
 		return tipc_node_suggest_addr(net, addr);
 
-	return addr;
+	return 0;
 }
 
 void tipc_node_check_dest(struct net *net, u32 addr,