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LibJS: Leave unwind context if it has no finalizer when using handler

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For example, a try/catch block with no finally. The try block and catch
block do not need to unwind to a finally block, so the unwind context
is no longer needed when we jump to the catch block.

If we threw an exception in a catch block of a try/catch, there will be
no handler or finalizer and the unit would continue on as if nothing
happened.

This would subsequently crash with the  `m_saved_exception.is_null()`
assertion failure when we next call a non-native function.
This commit is contained in:
Luke Wilde 2022-03-14 02:20:50 +00:00 • committed by Ali Mohammad Pur
parent 0356239f3e
commit ada8880f58
1 changed files with 8 additions and 0 deletions
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8
Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
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@ -92,6 +92,11 @@ Interpreter::ValueAndFrame Interpreter::run_and_return_frame(Executable const& e
if (unwind_context.handler) {
block = unwind_context.handler;
unwind_context.handler = nullptr;
// If there's no finalizer, there's nowhere for the handler block to unwind to, so the unwind context is no longer needed.
if (!unwind_context.finalizer)
m_unwind_contexts.take_last();
accumulator() = exception_value;
m_saved_exception = {};
will_jump = true;
@ -103,6 +108,9 @@ Interpreter::ValueAndFrame Interpreter::run_and_return_frame(Executable const& e
will_jump = true;
break;
}
// An unwind context with no handler or finalizer? We have nowhere to jump, and continuing on will make us crash on the next `Call` to a non-native function if there's an exception! So let's crash here instead.
// If you run into this, you probably forgot to remove the current unwind_context somewhere.
VERIFY_NOT_REACHED();
}
if (m_pending_jump.has_value()) {
block = m_pending_jump.release_value();