[issue21073] Py_ReprEnter potentially misbehaves during malformed thread states
New submission from Itai Bar-Natan: While browsing the Python source code, I found this suspicious snippet in Py_ReprEnter: dict = PyThreadState_GetDict(); if (dict == NULL) return 0; It seems to me like the last line should be "return -1;". The way the program currently behaves, if PyThreadState_GetDict() fails and returns NULL, Py_ReprEnter will fail silently and always report that the input isn't in a recursive loop. The correct behavior is to report an error. It would be difficult to explicitly exhibit this error since it relies on another component of Python failing first. One possible way would be to call PyObject_Repr on a recursive structure before fully initializing Python. I haven't tested this. Alternately, it's possible that this behavior is intentional because we want PyObject_Repr to work for non-self-referential structures even before Python is fully initialized (perhaps it could be called during initialization), in exchange for a small risk of failure if it is called with a self-referential structure before initialization. In that case I suggest that this should be pointed out explicitly in the comments to this function. -- components: Interpreter Core messages: 214920 nosy: itaibn priority: normal severity: normal status: open title: Py_ReprEnter potentially misbehaves during malformed thread states type: behavior versions: Python 2.7, Python 3.1, Python 3.2, Python 3.3, Python 3.4, Python 3.5 ___ Python tracker <http://bugs.python.org/issue21073> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue25631] Segmentation fault with invalid Unicode command-line arguments in embedded Python
New submission from Itai Bar-Natan:
The following embedded application, which calls Py_Main with a "-W X" argument
where X is not a valid Unicode string, returns a segmentation fault:
```
#include "Python.h"
main() {
wchar_t *invalid_str;
invalid_str = malloc(2*sizeof(wchar_t));
invalid_str[0] = 0x11;
invalid_str[1] = 0;
wchar_t *argv[4] = {L"embedded-python", L"-W", invalid_str, NULL};
Py_Main(3, argv);
}
```
This segmentation fault is present in Python 3.4, 3.5, and the latest
development branch I downloaded, but is not present in Python 3.2. This program
is obviously invalid and it may be reasonable to emit a fatal error in this
situation, but it should not give a segmentation fault.
I believe the issue is that this codes leads to exception being thrown before
exceptions are initialized, and more specifically, a call to
PyExceptionClass_Check() within PyErr_Object() reads a NULL pointer. I haven't
tested this but I expect that this problem would not appear when calling Python
directly since Python sanitizes the command line arguments from main().
Nonetheless even here the possibility of other exceptions being raised early in
the initialization sequence remains a potential problem.
--
components: Interpreter Core
messages: 254703
nosy: itaibn
priority: normal
severity: normal
status: open
title: Segmentation fault with invalid Unicode command-line arguments in
embedded Python
type: crash
versions: Python 3.4, Python 3.5, Python 3.6
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