[issue37985] WFERR_UNMARSHALLABLE breaks recursion limit

[Davis Herring]

New submission from Davis Herring <herring at lanl.gov>:

Most of the "p->depth--;" lines associated with "p->error = WFERR_UNMARSHALLABLE;" are spurious, and can crash the interpreter if enough of them prevent reaching MAX_MARSHAL_STACK_DEPTH.  (The only exceptions are in 2.7, where some of them are followed by a return that skips another "p->depth--;".)

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components: Interpreter Core
messages: 350841
nosy: herring
priority: normal
severity: normal
status: open
title: WFERR_UNMARSHALLABLE breaks recursion limit
type: crash
versions: Python 2.7, Python 3.5, Python 3.6, Python 3.7, Python 3.8, Python 3.9

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue37985>
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