In the interest of avoiding side-effects during dumping, I'm
replacing the value with a <constant ast> string instead of
performing an update constant operation.
Fixes a use-after-free encountered in Symfony's SecurityBundle.
I don't have a reproducer for this, and believe the issue can only
occur if we leak an iterator (the leak is a separate issue).
We should not free the generator iterator here, because we do not
own it. The code that fetched the iterator is responsible for
releasing it. In the rare case where we do hit this code-path,
we cause a use-after-free.
Always push the current user_error/exception_handler to the stack,
even when it is empty, so restore_error_handler() always works as
expected.
The user_error_handler is especially temporarily empty when we are inside
the error handler, which caused inconsistent behaviour before.
Unlink the current stack frame before freeing CVs or extra args.
This means it will no longer show up in back traces that are
generated during CV destruction.
We already did this prior to destructing the object/closure,
presumably for the same reason.
Finally blocks in generators may be invoked during shutdown, in
which case we don't have a stack frame. Similar to what
zend_call_function does, we still need to rethrow these exceptions,
otherwise they will be hidden (and leak).
The "return" in the for loop should have been a break on the switch,
otherwise the result is just ignored... but because it prevents
evaluation of the other operand, it also violates the invariant that
everything has been constant evaluated, resulting in an assertion
failure.
The for loop isn't correct in any case though, because it's not legal
to determine the result based on just the second operand, as the
first one may have a side-effect that cannot be optimized away.
And `$x = !$x`
Noticed while working on GH-4912
The included test would not emit undefined variable errors in php 8.0
with opcache enabled. The command used:
```
php -d zend_extension=opcache.so --no-php-ini -d error_reporting=E_ALL \
-d opcache.file_cache= -d opcache.enable_cli=1 test.php
```
NULL out the execute_data before destroying it, otherwise GC may
trigger while the execute_data is partially destroyed, resulting
in double-frees.
The handling of call stack unfreezing is a bit awkward because it's
a ZEND_API function, so we can't change the signature.
This originally manifested as a leak in oss-fuzz #18000. The following
is a reduced test case:
<?php
[
5 => 1,
"foo" > 1,
" " => "" == 0
];
<<<BAR
$x
BAR;
Because this particular error condition did not return T_ERROR,
EG(exception) was set while performing binary operation constant
evaluation, which checks exceptions for cast failures.
Instead of adding this indirect test case, I'm adding an assertion
that the lexer has to return T_ERROR if EG(exception) is set.
Christoph M. Becker