Fix int/size_t confusion in isValidPharFilename (bug #73580)

ext/phar/phar_object.c

@@ -1066,6 +1066,10 @@ PHP_METHOD(Phar, isValidPharFilename)
 		return;
 	}
 
+	if (ZEND_SIZE_T_INT_OVFL(fname_len)) {
+		RETURN_FALSE;
+	}
+
 	is_executable = executable;
 	RETVAL_BOOL(phar_detect_phar_fname_ext(fname, fname_len, &ext_str, &ext_len, is_executable, 2, 1) == SUCCESS);
 }