tipc: fix a memleak when sending data

This fixes a regression bug caused by:
067608e9d019d6477fd45dd948e81af0e5bf599f ("tipc: introduce direct
iovec to buffer chain fragmentation function")

If data is sent on a nonblocking socket and the destination link
is congested, the buffer chain is leaked. We fix this by freeing
the chain in this case.

Signed-off-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/socket.c

@@ -784,8 +784,9 @@ new_mtu:
 			break;
 
 		rc = tipc_wait_for_sndmsg(sock, &timeo);
+		if (rc)
+			kfree_skb_list(buf);
 	} while (!rc);
-
 exit:
 	if (iocb)
 		release_sock(sk);
@@ -898,6 +899,8 @@ next:
 				break;
 		}
 		rc = tipc_wait_for_sndpkt(sock, &timeo);
+		if (rc)
+			kfree_skb_list(buf);
 	} while (!rc);
 exit:
 	if (iocb)