Fix CodeValidator null deref after final END pops control stack#573
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titzer merged 3 commits intotitzer:masterfrom Mar 4, 2026
Merged
Fix CodeValidator null deref after final END pops control stack#573titzer merged 3 commits intotitzer:masterfrom
titzer merged 3 commits intotitzer:masterfrom
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After the final END opcode pops the last control frame, ctl_stack is empty but ctl_stack.peek() is called unconditionally to set ctl_top, resulting in a null dereference on subsequent opcode processing. The codeptr reset (to stop processing) was only applied when validatingInitExpr was true. Make the empty-stack check unconditional so that normal function validation also stops after the final END.
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titzer
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Mar 3, 2026
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Thanks, can you please add a regression test for this case?
Tests that the validator does not crash when the final END pops the last control frame and trailing bytes remain in the body.
Comment change to trigger CI rerun.
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Summary
ENDopcode pops the last control frame,ctl_stack.peek()is called to setctl_top, but the stack is empty, resulting in a null dereference on subsequent opcode processing.Details
CodeValidator.v3:373— thecodeptr.reset()(to stop processing) was only applied whenvalidatingInitExprwas true. Make the empty-stack check unconditional so normal function validation also stops after the final END.