gh-159739: Release resources on interpreter startup error paths

Release path-file read buffers on early return and the command string
when an audit hook rejects execution.

Backport to 3.15 and 3.14.

Author: JelleZijlstra

Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-19-33-35.gh-issue-159739.c25c27.rst

@@ -0,0 +1,2 @@
+Fix memory leaks during interpreter startup when a path configuration file is
+empty or too large, or when an audit hook rejects a command.

Modules/getpath.c

@@ -409,9 +409,11 @@ getpath_readlines_impl(PyObject *module, PyObject *pathobj)
     size_t cb = fread(buffer, 1, MAX_FILE, fp);
     fclose(fp);
     if (!cb) {
+        PyMem_Free(buffer);
         return r;
     }
     if (cb >= MAX_FILE) {
+        PyMem_Free(buffer);
         Py_DECREF(r);
         PyErr_SetString(PyExc_MemoryError,
             "cannot read file larger than 32KB during initialization");

Modules/main.c

@@ -286,6 +286,7 @@ pymain_run_command(wchar_t *command)
     }
 
     if (PySys_Audit("cpython.run_command", "O", unicode) < 0) {
+        Py_DECREF(unicode);
         return pymain_exit_err_print();
     }