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gh-83004: Harden msvcrt init #103383

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Apr 10, 2023
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41 changes: 29 additions & 12 deletions PC/msvcrtmodule.c
Original file line number Diff line number Diff line change
Expand Up @@ -609,11 +609,11 @@ PyMODINIT_FUNC
PyInit_msvcrt(void)
{
int st;
PyObject *d, *version;
PyObject *m = PyModule_Create(&msvcrtmodule);
if (m == NULL)
if (m == NULL) {
return NULL;
d = PyModule_GetDict(m);
}
PyObject *d = PyModule_GetDict(m); // Borrowed ref.

/* constants for the locking() function's mode argument */
insertint(d, "LK_LOCK", _LK_LOCK);
Expand Down Expand Up @@ -644,30 +644,47 @@ PyInit_msvcrt(void)
#ifdef _VC_ASSEMBLY_PUBLICKEYTOKEN
st = PyModule_AddStringConstant(m, "VC_ASSEMBLY_PUBLICKEYTOKEN",
_VC_ASSEMBLY_PUBLICKEYTOKEN);
if (st < 0) return NULL;
if (st < 0) {
goto error;
}
#endif
#ifdef _CRT_ASSEMBLY_VERSION
st = PyModule_AddStringConstant(m, "CRT_ASSEMBLY_VERSION",
_CRT_ASSEMBLY_VERSION);
if (st < 0) return NULL;
if (st < 0) {
goto error;
}
#endif
#ifdef __LIBRARIES_ASSEMBLY_NAME_PREFIX
st = PyModule_AddStringConstant(m, "LIBRARIES_ASSEMBLY_NAME_PREFIX",
__LIBRARIES_ASSEMBLY_NAME_PREFIX);
if (st < 0) return NULL;
if (st < 0) {
goto error;
}
#endif

/* constants for the 2010 crt versions */
#if defined(_VC_CRT_MAJOR_VERSION) && defined (_VC_CRT_MINOR_VERSION) && defined(_VC_CRT_BUILD_VERSION) && defined(_VC_CRT_RBUILD_VERSION)
version = PyUnicode_FromFormat("%d.%d.%d.%d", _VC_CRT_MAJOR_VERSION,
_VC_CRT_MINOR_VERSION,
_VC_CRT_BUILD_VERSION,
_VC_CRT_RBUILD_VERSION);
st = PyModule_AddObject(m, "CRT_ASSEMBLY_VERSION", version);
if (st < 0) return NULL;
PyObject *version = PyUnicode_FromFormat("%d.%d.%d.%d",
_VC_CRT_MAJOR_VERSION,
_VC_CRT_MINOR_VERSION,
_VC_CRT_BUILD_VERSION,
_VC_CRT_RBUILD_VERSION);
if (version == NULL) {
goto error;
}
st = PyModule_AddObjectRef(m, "CRT_ASSEMBLY_VERSION", version);
Comment on lines +673 to +676
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@erlend-aasland Just FYI, the modsupport functions allow passing in NULL provided an error has already occurred, and they just let it chain. So the code here was fine before.

No need to revert now though.

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TIL! Sorry for not waiting on your review.

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However, there was a leak if PyModule_AddObject failed, since that API only eat refs if successful.

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Sorry I should have been more careful in this.

Py_DECREF(version);
if (st < 0) {
goto error;
}
#endif
/* make compiler warning quiet if st is unused */
(void)st;

return m;

error:
Py_DECREF(m);
return NULL;
}