gtphub: check for gsn_addr_from_sockaddr() error

Change-Id: I2d80b5a488e7daa0bc8f57ea304e0e1f10f6c1f5
Fixes: CID182472
diff --git a/src/gprs/gtphub.c b/src/gprs/gtphub.c
index 2ff1b7c..4ee20cd 100644
--- a/src/gprs/gtphub.c
+++ b/src/gprs/gtphub.c
@@ -2649,7 +2649,9 @@
 {
 	struct gsn_addr gsna;
 	uint16_t port;
-	gsn_addr_from_sockaddr(&gsna, &port, addr);
+	if (gsn_addr_from_sockaddr(&gsna, &port, addr) != 0)
+		return NULL;
+
 	return gtphub_port_find(bind, &gsna, port);
 }