[PATCH v20 19/21] perf python: Add type checking for parse_events/parse_metrics

[Ian Rogers]

The threads and cpus parameters in parse_events and parse_metrics
are parsed with the 'O' format specifier but blindly casted in the
C extension. If a user passes an invalid object type, this leads to
memory corruption when dereferencing the expected struct.

Add runtime PyObject_TypeCheck validations in python.c to safely
raise a TypeError if an invalid object is passed.

Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
 tools/perf/util/python.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index 4ec5a91d45c0..11e1f39c1bea 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -3341,6 +3341,20 @@ static PyObject *pyrf__parse_events(PyObject *self, PyObject *args)
 		return NULL;
 	}
 
+	if (pthreads && pthreads != Py_None &&
+	    !PyObject_TypeCheck(pthreads, &pyrf_thread_map__type)) {
+		PyErr_SetString(PyExc_TypeError, "threads must be a perf.thread_map or None");
+		evlist__put(evlist);
+		return NULL;
+	}
+
+	if (pcpus && pcpus != Py_None &&
+	    !PyObject_TypeCheck(pcpus, &pyrf_cpu_map__type)) {
+		PyErr_SetString(PyExc_TypeError, "cpus must be a perf.cpu_map or None");
+		evlist__put(evlist);
+		return NULL;
+	}
+
 	threads = (pthreads && pthreads != Py_None) ?
 			((struct pyrf_thread_map *)pthreads)->threads : NULL;
 	cpus = (pcpus && pcpus != Py_None) ?
@@ -3377,6 +3391,20 @@ static PyObject *pyrf__parse_metrics(PyObject *self, PyObject *args)
 		return NULL;
 	}
 
+	if (pthreads && pthreads != Py_None &&
+	    !PyObject_TypeCheck(pthreads, &pyrf_thread_map__type)) {
+		PyErr_SetString(PyExc_TypeError, "threads must be a perf.thread_map or None");
+		evlist__put(evlist);
+		return NULL;
+	}
+
+	if (pcpus && pcpus != Py_None &&
+	    !PyObject_TypeCheck(pcpus, &pyrf_cpu_map__type)) {
+		PyErr_SetString(PyExc_TypeError, "cpus must be a perf.cpu_map or None");
+		evlist__put(evlist);
+		return NULL;
+	}
+
 	threads = (pthreads && pthreads != Py_None) ?
 			((struct pyrf_thread_map *)pthreads)->threads : NULL;
 	cpus = (pcpus && pcpus != Py_None) ?
-- 
2.54.0.1136.gdb2ca164c4-goog