[issue36386] segfault on PyUnicode_DecodeFSDefaultAndSize for uninitialized Py

[anthony shaw]

New submission from anthony shaw <anthony.p.shaw at gmail.com>:

If for whatever reason, Py_Initialize() has not been run or failed to run, any call to Py_CompileStringFlags will call PyUnicode_DecodeFSDefault and the reference to interp will be NULL.

There is currently no null reference check in PyUnicode_DecodeFSDefaultAndSize which causes a segfault.

https://github.com/python/cpython/blob/master/Objects/unicodeobject.c#L3736-L3737 is the offending line.

It might be better to catch the null pointer and raise an unrecoverable error there?

Error: signal 11:
0   ceval-prof                          0x00000001066310f3 handler + 35
1   libsystem_platform.dylib            0x00007fff6adddb3d _sigtramp + 29
2   ???                                 0x0000000000000000 0x0 + 0
3   ceval-prof                          0x0000000106734536 PyUnicode_DecodeFSDefault + 38
4   ceval-prof                          0x0000000106879514 Py_CompileStringExFlags + 36
5   ceval-prof                          0x0000000106631280 main + 320
6   libdyld.dylib                       0x00007fff6abf2ed9 start + 1

----------
components: Interpreter Core
messages: 338521
nosy: anthony shaw
priority: normal
severity: normal
status: open
title: segfault on PyUnicode_DecodeFSDefaultAndSize for uninitialized Py
versions: Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue36386>
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