Probably should be sizeof(char*) rather than sizeof(zval) here as zend extension paths are stored as a strings rather than zvals, as below. As a result the stack is blown on the resultant memcpy in the llist code.


zend_llist_init(&extension_lists.engine, sizeof(zval), (llist_dtor_func_t) free_estring, 1);
/*...*/
char *extension_name = estrndup(Z_STRVAL_P(arg2), Z_STRLEN_P(arg2));
					
zend_llist_add_element(&extension_lists.engine, &extension_name);