gh-130163: Fix crashes related to PySys_GetObject() (GH-130503)

The use of PySys_GetObject() and _PySys_GetAttr(), which return a borrowed
reference, has been replaced by using one of the following functions, which
return a strong reference and distinguish a missing attribute from an error:
_PySys_GetOptionalAttr(), _PySys_GetOptionalAttrString(),
_PySys_GetRequiredAttr(), and _PySys_GetRequiredAttrString().

1 files changed, 24 insertions, 12 deletions

diff --git a/Python/import.c b/Python/import.c
index 6d3b42941bd..6836e13972c 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -3326,19 +3326,15 @@ PyObject *
 PyImport_GetImporter(PyObject *path)
 {
     PyThreadState *tstate = _PyThreadState_GET();
-    PyObject *path_importer_cache = PySys_GetObject("path_importer_cache");
+    PyObject *path_importer_cache = _PySys_GetRequiredAttrString("path_importer_cache");
     if (path_importer_cache == NULL) {
-        PyErr_SetString(PyExc_RuntimeError, "lost sys.path_importer_cache");
         return NULL;
     }
-    Py_INCREF(path_importer_cache);
-    PyObject *path_hooks = PySys_GetObject("path_hooks");
+    PyObject *path_hooks = _PySys_GetRequiredAttrString("path_hooks");
     if (path_hooks == NULL) {
-        PyErr_SetString(PyExc_RuntimeError, "lost sys.path_hooks");
         Py_DECREF(path_importer_cache);
         return NULL;
     }
-    Py_INCREF(path_hooks);
     PyObject *importer = get_path_importer(tstate, path_importer_cache, path_hooks, path);
     Py_DECREF(path_hooks);
     Py_DECREF(path_importer_cache);
@@ -3640,15 +3636,31 @@ import_find_and_load(PyThreadState *tstate, PyObject *abs_name)
 
     PyTime_t t1 = 0, accumulated_copy = accumulated;
 
-    PyObject *sys_path = PySys_GetObject("path");
-    PyObject *sys_meta_path = PySys_GetObject("meta_path");
-    PyObject *sys_path_hooks = PySys_GetObject("path_hooks");
+    PyObject *sys_path, *sys_meta_path, *sys_path_hooks;
+    if (_PySys_GetOptionalAttrString("path", &sys_path) < 0) {
+        return NULL;
+    }
+    if (_PySys_GetOptionalAttrString("meta_path", &sys_meta_path) < 0) {
+        Py_XDECREF(sys_path);
+        return NULL;
+    }
+    if (_PySys_GetOptionalAttrString("path_hooks", &sys_path_hooks) < 0) {
+        Py_XDECREF(sys_meta_path);
+        Py_XDECREF(sys_path);
+        return NULL;
+    }
     if (_PySys_Audit(tstate, "import", "OOOOO",
                      abs_name, Py_None, sys_path ? sys_path : Py_None,
                      sys_meta_path ? sys_meta_path : Py_None,
                      sys_path_hooks ? sys_path_hooks : Py_None) < 0) {
+        Py_XDECREF(sys_path_hooks);
+        Py_XDECREF(sys_meta_path);
+        Py_XDECREF(sys_path);
         return NULL;
     }
+    Py_XDECREF(sys_path_hooks);
+    Py_XDECREF(sys_meta_path);
+    Py_XDECREF(sys_path);
 
 
     /* XOptions is initialized after first some imports.
@@ -4074,10 +4086,8 @@ _PyImport_FiniCore(PyInterpreterState *interp)
 static int
 init_zipimport(PyThreadState *tstate, int verbose)
 {
-    PyObject *path_hooks = PySys_GetObject("path_hooks");
+    PyObject *path_hooks = _PySys_GetRequiredAttrString("path_hooks");
     if (path_hooks == NULL) {
-        _PyErr_SetString(tstate, PyExc_RuntimeError,
-                         "unable to get sys.path_hooks");
         return -1;
     }
 
@@ -4097,12 +4107,14 @@ init_zipimport(PyThreadState *tstate, int verbose)
         int err = PyList_Insert(path_hooks, 0, zipimporter);
         Py_DECREF(zipimporter);
         if (err < 0) {
+            Py_DECREF(path_hooks);
             return -1;
         }
         if (verbose) {
             PySys_WriteStderr("# installed zipimport hook\n");
         }
     }
+    Py_DECREF(path_hooks);
 
     return 0;
 }