tipc: fix skb may be leaky in tipc_link_input

mainline inclusion
from mainline-5.0
commit 7384b538
category: bugfix
bugzilla: NA
CVE: NA

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

When we free skb at tipc_data_input, we return a 'false' boolean.
Then, skb passed to subcalling tipc_link_input in tipc_link_rcv,

<snip>
1303 int tipc_link_rcv:
...
1354    if (!tipc_data_input(l, skb, l->inputq))
1355        rc |= tipc_link_input(l, skb, l->inputq);
</snip>

Fix it by simple changing to a 'true' boolean when skb is being free-ed.
Then, tipc_link_rcv will bypassed to subcalling tipc_link_input as above
condition.
Acked-by: NYing Xue <ying.xue@windriver.com>
Acked-by: NJon Maloy <maloy@donjonn.com>
Signed-off-by: NHoang Le <hoang.h.le@dektech.com.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NZhiqiang Liu <liuzhiqiang26@huawei.com>
Reviewed-by: NMao Wenan <maowenan@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

net/tipc/link.c

@@ -1107,7 +1107,7 @@ static bool tipc_data_input(struct tipc_link *l, struct sk_buff *skb,
 	default:
 		pr_warn("Dropping received illegal msg type\n");
 		kfree_skb(skb);
-		return false;
+		return true;
 	};
 }