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[3.11] gh-105375: Harden pyexpat initialisation (#105606) (#105668)

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(cherry picked from commit 20a56d8bec)

Add proper error handling to add_errors_module() to prevent exceptions
from possibly being overwritten.
This commit is contained in:
Erlend E. Aasland 2023-06-11 23:28:12 +02:00 • committed by GitHub
parent f98d475ee3
commit e5fe017143
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2 changed files with 15 additions and 10 deletions
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3
Misc/NEWS.d/next/Library/2023-06-09-23-00-13.gh-issue-105605.YuwqxY.rst Normal file
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@ -0,0 +1,3 @@
Harden :mod:`pyexpat` error handling during module initialisation to prevent
exceptions from possibly being overwritten, and objects from being
dereferenced twice.

22
Modules/pyexpat.c
View file

@ -1768,14 +1768,18 @@ add_error(PyObject *errors_module, PyObject *codes_dict,
static int static int
add_errors_module(PyObject *mod) add_errors_module(PyObject *mod)
{ {
// add_submodule() returns a borrowed ref.
PyObject *errors_module = add_submodule(mod, MODULE_NAME ".errors"); PyObject *errors_module = add_submodule(mod, MODULE_NAME ".errors");
if (errors_module == NULL) { if (errors_module == NULL) {
return -1; return -1;
} }
PyObject *codes_dict = PyDict_New(); PyObject *codes_dict = PyDict_New();
if (codes_dict == NULL) {
return -1;
}
PyObject *rev_codes_dict = PyDict_New(); PyObject *rev_codes_dict = PyDict_New();
if (codes_dict == NULL || rev_codes_dict == NULL) { if (rev_codes_dict == NULL) {
goto error; goto error;
} }
@ -1796,19 +1800,17 @@ add_errors_module(PyObject *mod)
goto error; goto error;
} }
Py_INCREF(codes_dict); int rc = PyModule_AddObjectRef(errors_module, "codes", codes_dict);
if (PyModule_AddObject(errors_module, "codes", codes_dict) < 0) {
Py_DECREF(codes_dict);
goto error;
}
Py_CLEAR(codes_dict); Py_CLEAR(codes_dict);
if (rc < 0) {
Py_INCREF(rev_codes_dict);
if (PyModule_AddObject(errors_module, "messages", rev_codes_dict) < 0) {
Py_DECREF(rev_codes_dict);
goto error; goto error;
} }
rc = PyModule_AddObjectRef(errors_module, "messages", rev_codes_dict);
Py_CLEAR(rev_codes_dict); Py_CLEAR(rev_codes_dict);
if (rc < 0) {
goto error;
}
return 0; return 0;