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NewInstanceOperator fails to check returned class before initiating object. #1885

davidofferman opened this issue Jul 12, 2019 · 0 comments


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commented Jul 12, 2019

There is a problem when using the new instance operator. I believe I finally tracked down the issue that required the fix phalcon/cphalcon#14238 in cphalcon. I'm not familiar with the source code for the php interpreter or zephir, so please bear with me.

Currently, when using the new {classname}() operator in zep files, the following C code is generated.

zephir_fetch_safe_class(&_0$$3, &definition);
_1$$3 = zephir_fetch_class_str_ex(Z_STRVAL_P(&_0$$3), Z_STRLEN_P(&_0$$3), ZEND_FETCH_CLASS_AUTO);
object_init_ex(&handler, _1$$3);
if (zephir_has_constructor(&handler TSRMLS_CC)) {
    ZEPHIR_CALL_METHOD(NULL, &handler, "__construct", NULL, 0);

The problem is that the function zephir_fetch_class_str_ex will return NULL if the autoloaded class as a syntax error. This goes unchecked when passing it into object_init_ex which expects the handler to be valid since there isn't any guard in place.

That's why using zephir_create_instance() instead of new {classname}() doesn't cause a segfault.

Hopefully someone with more knowledge of Zephir can implement this fix. If not, I should be able to work on it in a few weeks. I'm working on a patch for this right now.

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