Hello internals, While working on some DNF type bugs, I discovered some major issues around the disable_classes INI setting implementation. Such as:
- A double-free of the type of a typed property - A use after free (which segfaults) when trying to access a property defined on a disabled class that was extended (e.g. disabling Exception) - A use after free when var_dumping a disabled class that has its own handler (as it will assume properties to be allocated) - And likely more considering the lack of tests surrounding this feature This feature seems of dubious nature, and the only justification given when adding support for this in the changelog of PHP 4.3.2 is: New "disable_classes" php.ini option to allow administrators to disable certain classes for security reasons. [1] However, only classes defined by extensions can be disabled, and such a class is critical for the correct operation of said extension. As such, what one should do for security reasons is to not enable the extension in the first place. Moreover, compared to the behaviour of disable_functions which, as of PHP 8.0, removes the function declaration completely, disable_classes does not remove the declaration of the class, but just "overloads" the object creation process to not initialize the object and emit a warning. Meaning, it is totally valid to instantiate a disabled class and pass it around to functions for them to blow up when they try to use the object as intended. Considering the major flaws in the implementation of said feature, the dubious nature of it, and the seeming lack of usage of it (considering none of the above breaking bugs have been reported). I would like to remove this feature in PHP 8.3, even though I know we are past feature freeze and close to the first RC. I have CCed the RMs for 8.3, and would like the opinion of other people on if this removal makes sense to the majority of people Sincerely, George P. Banyard [1] https://externals.io/message/2076
