[3.15] Fix unchecked NULL returns in several C modules (GH-160213) (#160262)

(cherry picked from commit a930e52)

Author: StanFromIreland

Modules/_elementtree.c

@@ -4210,6 +4210,9 @@ _elementtree_XMLParser__setevents_impl(XMLParserObject *self,
     if (events_to_report == Py_None) {
         /* default is "end" only */
         target->end_event_obj = PyUnicode_FromString("end");
+        if (target->end_event_obj == NULL) {
+            return NULL;
+        }
         Py_RETURN_NONE;
     }
 

Modules/_io/winconsoleio.c

@@ -962,6 +962,10 @@ _io__WindowsConsoleIO_readall_impl(winconsoleio *self)
 
     bytes_size += _buflen(self);
     bytes = PyBytes_FromStringAndSize(NULL, bytes_size);
+    if (bytes == NULL) {
+        PyMem_Free(buf);
+        return NULL;
+    }
     rn = _copyfrombuf(self, PyBytes_AS_STRING(bytes), bytes_size);
 
     if (len) {

Modules/_testinternalcapi.c

@@ -2581,6 +2581,9 @@ get_crossinterp_data(PyObject *self, PyObject *args, PyObject *kwargs)
     }
     else {
         mode = PyUnicode_AsUTF8(modeobj);
+        if (mode == NULL) {
+            return NULL;
+        }
         if (strlen(mode) == 0) {
             mode = "xidata";
         }

Modules/_xxtestfuzz/fuzzer.c

@@ -325,6 +325,10 @@ static int fuzz_sre_match(const char* data, size_t size) {
 
     PyObject* pattern = compiled_patterns[idx];
     PyObject* match_callable = PyObject_GetAttrString(pattern, "match");
+    if (match_callable == NULL) {
+        Py_DECREF(to_match);
+        return 0;
+    }
 
     PyObject* matches = PyObject_CallOneArg(match_callable, to_match);
 

Modules/getpath.c

@@ -591,7 +591,11 @@ getpath_warn(PyObject *Py_UNUSED(self), PyObject *args)
     if (!PyArg_ParseTuple(args, "U", &msgobj)) {
         return NULL;
     }
-    fprintf(stderr, "%s\n", PyUnicode_AsUTF8(msgobj));
+    const char *msg = PyUnicode_AsUTF8(msgobj);
+    if (msg == NULL) {
+        return NULL;
+    }
+    fprintf(stderr, "%s\n", msg);
     Py_RETURN_NONE;
 }
 

Modules/posixmodule.c

@@ -5696,8 +5696,9 @@ os__getvolumepathname_impl(PyObject *module, path_t *path)
         goto exit;
     }
     result = PyUnicode_FromWideChar(mountpath, -1);
-    if (PyBytes_Check(path->object))
+    if (result != NULL && PyBytes_Check(path->object)) {
         Py_SETREF(result, PyUnicode_EncodeFSDefault(result));
+    }
 
 exit:
     PyMem_Free(mountpath);

Modules/readline.c

@@ -1508,10 +1508,19 @@ flex_complete(const char *text, int start, int end)
 
 done:
     if (state) {
-        Py_XDECREF(state->begidx);
-        Py_XDECREF(state->endidx);
-        state->begidx = PyLong_FromLong((long) start);
-        state->endidx = PyLong_FromLong((long) end);
+        PyObject *begidx = PyLong_FromLong((long) start);
+        PyObject *endidx = PyLong_FromLong((long) end);
+        if (begidx == NULL || endidx == NULL) {
+            Py_XDECREF(begidx);
+            Py_XDECREF(endidx);
+            PyErr_FormatUnraisable("Exception ignored while preparing "
+                                   "readline completion");
+            rl_attempted_completion_over = 1;
+            PyGILState_Release(gilstate);
+            return NULL;
+        }
+        Py_XSETREF(state->begidx, begidx);
+        Py_XSETREF(state->endidx, endidx);
     }
     result = completion_matches((char *)text, *on_completion);
     PyGILState_Release(gilstate);

Modules/socketmodule.c

@@ -1766,6 +1766,9 @@ makesockaddr(SOCKET_T sockfd, struct sockaddr *addr, size_t addrlen, int proto)
         PyObject *vmId = PyUnicode_FromWideChar(guidStr, -1);
         res = RpcStringFreeW(&guidStr);
         assert(res == RPC_S_OK);
+        if (vmId == NULL) {
+            return 0;
+        }
 
         res = UuidToStringW(&a->ServiceId, &guidStr);
         if (res != RPC_S_OK) {

Python/ceval.c

@@ -1199,8 +1199,16 @@ dtrace_function_entry(_PyInterpreterFrame *frame)
     int lineno;
 
     PyCodeObject *code = _PyFrame_GetCode(frame);
+    PyObject *exc = PyErr_GetRaisedException();
     filename = PyUnicode_AsUTF8(code->co_filename);
     funcname = PyUnicode_AsUTF8(code->co_name);
+    PyErr_SetRaisedException(exc);
+    if (filename == NULL) {
+        filename = "<unknown>";
+    }
+    if (funcname == NULL) {
+        funcname = "<unknown>";
+    }
     lineno = PyUnstable_InterpreterFrame_GetLine(frame);
 
     PyDTrace_FUNCTION_ENTRY(filename, funcname, lineno);
@@ -1214,8 +1222,16 @@ dtrace_function_return(_PyInterpreterFrame *frame)
     int lineno;
 
     PyCodeObject *code = _PyFrame_GetCode(frame);
+    PyObject *exc = PyErr_GetRaisedException();
     filename = PyUnicode_AsUTF8(code->co_filename);
     funcname = PyUnicode_AsUTF8(code->co_name);
+    PyErr_SetRaisedException(exc);
+    if (filename == NULL) {
+        filename = "<unknown>";
+    }
+    if (funcname == NULL) {
+        funcname = "<unknown>";
+    }
     lineno = PyUnstable_InterpreterFrame_GetLine(frame);
 
     PyDTrace_FUNCTION_RETURN(filename, funcname, lineno);

Python/crossinterp.c

@@ -664,6 +664,11 @@ check_missing___main___attr(PyObject *exc)
         }
     }
     const char *err = PyUnicode_AsUTF8(msgobj);
+    if (err == NULL) {
+        PyErr_Clear();
+        Py_DECREF(msgobj);
+        return 0;
+    }
 
     // Check if it's a missing __main__ attr.
     int cmp = strncmp(err, "module '__main__' has no attribute '", 36);