core: init the len of sock_str attribute

(cherry picked from commit f0d89fb89d1b588f253f048ab8fc22e0db7fff66)

socket_info.c

@@ -363,6 +363,7 @@ static int fix_sock_str(struct socket_info* si)
 		return -1;
 	}
 	si->sock_str.s[len] = '\0';
+	si->sock_str.len = len;
 	return 0;
 }