python / python/cpython

Many places have missing `PyErr_NoMemory()` call after failing memory allocation

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Since Jun 9, 2026.

interpreter-core type-crash
Dominant language
Python
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Description

Crash report

  1. remove_unused_consts in Python/flowgraph.c

When PyMem_Malloc(nconsts * sizeof(Py_ssize_t)); fails, we need to set an exception.

https://github.com/python/cpython/blob/29a920e80e21490b5bdb7178373f80fe606a4403/Python/flowgraph.c#L3267-L3283

  1. gethandlelist and getattributelist in _winapi.c

This place misses it:

https://github.com/python/cpython/blob/9fdbade99e6bcc607d9f12416bfca5bbf94022b9/Modules/_winapi.c#L1196-L1198

All other error paths set exceptions, except this if:

https://github.com/python/cpython/blob/9fdbade99e6bcc607d9f12416bfca5bbf94022b9/Modules/_winapi.c#L1278-L1282

  1. _channelends_new in Modules/_interpchannelsmodule.c

https://github.com/python/cpython/blob/3ca93ab198497da9451101019b67c52e7873377d/Modules/_interpchannelsmodule.c#L920-L926

Later we check for errors in handle_channel_error, it requires either setting err to non -1 or to set Python exception. Both are false, it fails with the assertion failure.

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