Add stack limit check in zend_eval_const_expr() #11424
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iluuu1994
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Jun 27, 2023
Zend/zend_compile.c
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| #ifdef ZEND_CHECK_STACK_LIMIT | ||
| if (UNEXPECTED(zend_call_stack_overflowed(EG(stack_limit)))) { | ||
| /* Abort evaluation due to stack usage. Note that compiling this | ||
| * expression is likely to also fail. */ |
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Not sure if this is a real problem but zend_eval_const_expr evaluates some AST nodes that must not appear again in constant expressions, e.g. magic constants. It might be better to fatal error right here too, in case the expression evaluation uses fewer stack frames than zend_eval_const_expr.
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Add a stack limit check to avoid stack overflows when trying to evaluate very large expressions.
This is similar to the check in zend_compile_expr(), but instead of bailing out, we can just skip evaluation (although this still bailouts afterwards if the expression is compiled).