[3.12] gh-107913: Fix possible losses of OSError error codes (GH-107930) (#108523)

gh-107913: Fix possible losses of OSError error codes (GH-107930) Functions like PyErr_SetFromErrno() and SetFromWindowsErr() should be called immediately after using the C API which sets errno or the Windows error code. (cherry picked from commit 2b15536) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

Author: miss-islington

Misc/NEWS.d/next/Library/2023-08-14-11-18-13.gh-issue-107913.4ooY6i.rst

@@ -0,0 +1,3 @@
+Fix possible losses of ``errno`` and ``winerror`` values in :exc:`OSError`
+exceptions if they were cleared or modified by the cleanup code before
+creating the exception object.

Modules/_cursesmodule.c

@@ -3071,8 +3071,8 @@ _curses_getwin(PyObject *module, PyObject *file)
  }
  datalen = PyBytes_GET_SIZE(data);
  if (fwrite(PyBytes_AS_STRING(data), 1, datalen, fp) != datalen) {
- Py_DECREF(data);
  PyErr_SetFromErrno(PyExc_OSError);
+ Py_DECREF(data);
  goto error;
  }
  Py_DECREF(data);

Modules/_io/fileio.c

@@ -394,6 +394,11 @@ _io_FileIO___init___impl(fileio *self, PyObject *nameobj, const char *mode,
 
  if (async_err)
  goto error;
+
+ if (self->fd < 0) {
+ PyErr_SetFromErrnoWithFilenameObject(PyExc_OSError, nameobj);
+ goto error;
+ }
  }
  else {
  PyObject *fdobj;
@@ -425,12 +430,7 @@ _io_FileIO___init___impl(fileio *self, PyObject *nameobj, const char *mode,
  goto error;
  }
  }
-
  fd_is_own = 1;
- if (self->fd < 0) {
- PyErr_SetFromErrnoWithFilenameObject(PyExc_OSError, nameobj);
- goto error;
- }
 
 #ifndef MS_WINDOWS
  if (_Py_set_inheritable(self->fd, 0, atomic_flag_works) < 0)
@@ -1058,8 +1058,8 @@ _io_FileIO_truncate_impl(fileio *self, PyTypeObject *cls, PyObject *posobj)
  Py_END_ALLOW_THREADS
 
  if (ret != 0) {
- Py_DECREF(posobj);
  PyErr_SetFromErrno(PyExc_OSError);
+ Py_DECREF(posobj);
  return NULL;
  }
 

Modules/_io/winconsoleio.c

@@ -378,8 +378,8 @@ _io__WindowsConsoleIO___init___impl(winconsoleio *self, PyObject *nameobj,
  else
  self->fd = _Py_open_osfhandle_noraise(handle, _O_RDONLY | _O_BINARY);
  if (self->fd < 0) {
- CloseHandle(handle);
  PyErr_SetFromErrnoWithFilenameObject(PyExc_OSError, nameobj);
+ CloseHandle(handle);
  goto error;
  }
  }

Modules/_localemodule.c

@@ -737,8 +737,8 @@ _locale_bindtextdomain_impl(PyObject *module, const char *domain,
  }
  current_dirname = bindtextdomain(domain, dirname);
  if (current_dirname == NULL) {
- Py_XDECREF(dirname_bytes);
  PyErr_SetFromErrno(PyExc_OSError);
+ Py_XDECREF(dirname_bytes);
  return NULL;
  }
  result = PyUnicode_DecodeLocale(current_dirname, NULL);

Modules/_multiprocessing/semaphore.c

@@ -516,12 +516,12 @@ _multiprocessing_SemLock_impl(PyTypeObject *type, int kind, int value,
  return result;
 
  failure:
- if (handle != SEM_FAILED)
- SEM_CLOSE(handle);
- PyMem_Free(name_copy);
  if (!PyErr_Occurred()) {
  _PyMp_SetError(NULL, MP_STANDARD_ERROR);
  }
+ if (handle != SEM_FAILED)
+ SEM_CLOSE(handle);
+ PyMem_Free(name_copy);
  return NULL;
 }
 
@@ -556,8 +556,9 @@ _multiprocessing_SemLock__rebuild_impl(PyTypeObject *type, SEM_HANDLE handle,
  if (name != NULL) {
  handle = sem_open(name, 0);
  if (handle == SEM_FAILED) {
+ PyErr_SetFromErrno(PyExc_OSError);
  PyMem_Free(name_copy);
- return PyErr_SetFromErrno(PyExc_OSError);
+ return NULL;
  }
  }
 #endif

Modules/_ssl.c

@@ -3889,8 +3889,8 @@ _ssl__SSLContext_load_cert_chain_impl(PySSLContext *self, PyObject *certfile,
  /* the password callback has already set the error information */
  }
  else if (errno != 0) {
- ERR_clear_error();
  PyErr_SetFromErrno(PyExc_OSError);
+ ERR_clear_error();
  }
  else {
  _setSSLError(get_state_ctx(self), NULL, 0, __FILE__, __LINE__);
@@ -3910,8 +3910,8 @@ _ssl__SSLContext_load_cert_chain_impl(PySSLContext *self, PyObject *certfile,
  /* the password callback has already set the error information */
  }
  else if (errno != 0) {
- ERR_clear_error();
  PyErr_SetFromErrno(PyExc_OSError);
+ ERR_clear_error();
  }
  else {
  _setSSLError(get_state_ctx(self), NULL, 0, __FILE__, __LINE__);
@@ -4140,8 +4140,8 @@ _ssl__SSLContext_load_verify_locations_impl(PySSLContext *self,
  PySSL_END_ALLOW_THREADS
  if (r != 1) {
  if (errno != 0) {
- ERR_clear_error();
  PyErr_SetFromErrno(PyExc_OSError);
+ ERR_clear_error();
  }
  else {
  _setSSLError(get_state_ctx(self), NULL, 0, __FILE__, __LINE__);
@@ -4188,8 +4188,8 @@ _ssl__SSLContext_load_dh_params(PySSLContext *self, PyObject *filepath)
  PySSL_END_ALLOW_THREADS
  if (dh == NULL) {
  if (errno != 0) {
- ERR_clear_error();
  PyErr_SetFromErrnoWithFilenameObject(PyExc_OSError, filepath);
+ ERR_clear_error();
  }
  else {
  _setSSLError(get_state_ctx(self), NULL, 0, __FILE__, __LINE__);

Modules/faulthandler.c

@@ -414,11 +414,10 @@ faulthandler_allocate_stack(void)
 
  int err = sigaltstack(&stack, &old_stack);
  if (err) {
+ PyErr_SetFromErrno(PyExc_OSError);
  /* Release the stack to retry sigaltstack() next time */
  PyMem_Free(stack.ss_sp);
  stack.ss_sp = NULL;
-
- PyErr_SetFromErrno(PyExc_OSError);
  return -1;
  }
  return 0;

Modules/fcntlmodule.c

@@ -211,11 +211,12 @@ fcntl_ioctl_impl(PyObject *module, int fd, unsigned int code,
  if (mutate_arg && (len <= IOCTL_BUFSZ)) {
  memcpy(str, buf, len);
  }
- PyBuffer_Release(&pstr); /* No further access to str below this point */
  if (ret < 0) {
  PyErr_SetFromErrno(PyExc_OSError);
+ PyBuffer_Release(&pstr);
  return NULL;
  }
+ PyBuffer_Release(&pstr);
  if (mutate_arg) {
  return PyLong_FromLong(ret);
  }
@@ -240,8 +241,8 @@ fcntl_ioctl_impl(PyObject *module, int fd, unsigned int code,
  ret = ioctl(fd, code, buf);
  Py_END_ALLOW_THREADS
  if (ret < 0) {
- PyBuffer_Release(&pstr);
  PyErr_SetFromErrno(PyExc_OSError);
+ PyBuffer_Release(&pstr);
  return NULL;
  }
  PyBuffer_Release(&pstr);

Modules/getpath.c

@@ -341,11 +341,12 @@ getpath_readlines(PyObject *Py_UNUSED(self), PyObject *args)
  return NULL;
  }
  FILE *fp = _Py_wfopen(path, L"rb");
- PyMem_Free((void *)path);
  if (!fp) {
  PyErr_SetFromErrno(PyExc_OSError);
+ PyMem_Free((void *)path);
  return NULL;
  }
+ PyMem_Free((void *)path);
 
  r = PyList_New(0);
  if (!r) {