tipc: use only positive error codes in messages

BugLink: http://bugs.launchpad.net/bugs/1729105


[ Upstream commit aad06212 ]

In commit e3a77561 ("tipc: split up function tipc_msg_eval()"),
we have updated the function tipc_msg_lookup_dest() to set the error
codes to negative values at destination lookup failures. Thus when
the function sets the error code to -TIPC_ERR_NO_NAME, its inserted
into the 4 bit error field of the message header as 0xf instead of
TIPC_ERR_NO_NAME (1). The value 0xf is an unknown error code.

In this commit, we set only positive error code.

Fixes: e3a77561 ("tipc: split up function tipc_msg_eval()")
Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

net/tipc/msg.c

@@ -541,7 +541,7 @@ bool tipc_msg_lookup_dest(struct net *net, struct sk_buff *skb, int *err)
 		return false;
 	if (msg_errcode(msg))
 		return false;
-	*err = -TIPC_ERR_NO_NAME;
+	*err = TIPC_ERR_NO_NAME;
 	if (skb_linearize(skb))
 		return false;
 	msg = buf_msg(skb);