gh-116180: Check the globals argument in PyRun_* C API (GH-116637)

It used to crash when passing NULL or non-dict as globals.
Now it sets a SystemError.

1 files changed, 12 insertions, 9 deletions

diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 2970248..31213ae 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -1275,17 +1275,20 @@ run_eval_code_obj(PyThreadState *tstate, PyCodeObject *co, PyObject *globals, Py
     _PyRuntime.signals.unhandled_keyboard_interrupt = 0;
 
     /* Set globals['__builtins__'] if it doesn't exist */
-    if (globals != NULL) {
-        int has_builtins = PyDict_ContainsString(globals, "__builtins__");
-        if (has_builtins < 0) {
+    if (!globals || !PyDict_Check(globals)) {
+        PyErr_SetString(PyExc_SystemError, "globals must be a real dict");
+        return NULL;
+    }
+    int has_builtins = PyDict_ContainsString(globals, "__builtins__");
+    if (has_builtins < 0) {
+        return NULL;
+    }
+    if (!has_builtins) {
+        if (PyDict_SetItemString(globals, "__builtins__",
+                                 tstate->interp->builtins) < 0)
+        {
             return NULL;
         }
-        if (!has_builtins) {
-            if (PyDict_SetItemString(globals, "__builtins__",
-                                     tstate->interp->builtins) < 0) {
-                return NULL;
-            }
-        }
     }
 
     v = PyEval_EvalCode((PyObject*)co, globals, locals);