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Prevent crashes on bare Varbind arguments #17

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Merged
SoundGoof merged 1 commit into from
Jul 23, 2026
Merged

Prevent crashes on bare Varbind arguments #17

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44 changes: 36 additions & 8 deletions netsnmp/client_intf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1535,8 +1535,12 @@ netsnmp_get(PyObject *self, PyObject *args)

if (varlist) {
PyObject *varlist_iter = PyObject_GetIter(varlist);
if (!varlist_iter) {
snmp_free_pdu(pdu);
goto done;
}

while (varlist_iter && (varbind = PyIter_Next(varlist_iter))) {
while ((varbind = PyIter_Next(varlist_iter))) {
if (py_netsnmp_attr_string(varbind, "tag", &tag, NULL) < 0 ||
py_netsnmp_attr_string(varbind, "iid", &iid, NULL) < 0)
{
Expand Down Expand Up @@ -1682,6 +1686,10 @@ netsnmp_get(PyObject *self, PyObject *args)

done:
SAFE_FREE(oid_arr);
if (PyErr_Occurred()) {
Py_XDECREF(val_tuple);
return NULL;
}
return (val_tuple ? val_tuple : Py_BuildValue(""));
}

Expand Down Expand Up @@ -1753,8 +1761,12 @@ netsnmp_getnext(PyObject *self, PyObject *args)

if (varlist) {
PyObject *varlist_iter = PyObject_GetIter(varlist);
if (!varlist_iter) {
snmp_free_pdu(pdu);
goto done;
}

while (varlist_iter && (varbind = PyIter_Next(varlist_iter))) {
while ((varbind = PyIter_Next(varlist_iter))) {
if (py_netsnmp_attr_string(varbind, "tag", &tag, NULL) < 0 ||
py_netsnmp_attr_string(varbind, "iid", &iid, NULL) < 0)
{
Expand Down Expand Up @@ -1902,6 +1914,10 @@ netsnmp_getnext(PyObject *self, PyObject *args)

done:
SAFE_FREE(oid_arr);
if (PyErr_Occurred()) {
Py_XDECREF(val_tuple);
return NULL;
}
return (val_tuple ? val_tuple : Py_BuildValue(""));
}

Expand Down Expand Up @@ -1991,8 +2007,12 @@ netsnmp_walk(PyObject *self, PyObject *args)

/* we need an initial count for memory allocation */
varlist_iter = PyObject_GetIter(varlist);
if (!varlist_iter) {
snmp_free_pdu(pdu);
goto done;
}
varlist_len = 0;
while (varlist_iter && (varbind = PyIter_Next(varlist_iter))) {
while ((varbind = PyIter_Next(varlist_iter))) {
varlist_len++;
}
Py_DECREF(varlist_iter);
Expand Down Expand Up @@ -2523,14 +2543,16 @@ netsnmp_getbulk(PyObject *self, PyObject *args)
/* propagate error */
if (verbose)
printf("error: getbulk response processing: unknown python error");
if (val_tuple)
Py_DECREF(val_tuple);
val_tuple = NULL;
Py_CLEAR(val_tuple);
}
}

done:
SAFE_FREE(oid_arr);
if (PyErr_Occurred()) {
Py_XDECREF(val_tuple);
return NULL;
}
return (val_tuple ? val_tuple : Py_BuildValue(""));
}

Expand All @@ -2539,7 +2561,7 @@ netsnmp_set(PyObject *self, PyObject *args)
{
PyObject *session;
PyObject *varlist;
PyObject *varbind;
PyObject *varbind = NULL;
PyObject *ret = NULL;
netsnmp_session *ss;
netsnmp_pdu *pdu, *response;
Expand Down Expand Up @@ -2587,8 +2609,12 @@ netsnmp_set(PyObject *self, PyObject *args)

if (varlist) {
PyObject *varlist_iter = PyObject_GetIter(varlist);
if (!varlist_iter) {
snmp_free_pdu(pdu);
goto done;
}

while (varlist_iter && (varbind = PyIter_Next(varlist_iter))) {
while ((varbind = PyIter_Next(varlist_iter))) {
if (py_netsnmp_attr_string(varbind, "tag", &tag, NULL) < 0 ||
py_netsnmp_attr_string(varbind, "iid", &iid, NULL) < 0)
{
Expand Down Expand Up @@ -2673,6 +2699,8 @@ netsnmp_set(PyObject *self, PyObject *args)
done:
Py_XDECREF(varbind);
SAFE_FREE(oid_arr);
if (PyErr_Occurred())
return NULL;
return (ret ? ret : Py_BuildValue(""));
}

Expand Down
17 changes: 17 additions & 0 deletions netsnmp/tests/system/test_errors.py
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,23 @@


class ErrorPathTests(unittest.TestCase):
def test_session_methods_reject_bare_varbind(self):
session = netsnmp.Session(**READ_ARGS)
varbind = netsnmp.Varbind(
'.1.3.6.1.2.1.1.3', '0', b'1', 'INTEGER')
calls = (
(TypeError, lambda: session.get(varbind)),
(TypeError, lambda: session.getnext(varbind)),
(TypeError, lambda: session.set(varbind)),
(AttributeError, lambda: session.walk(varbind)),
(AttributeError, lambda: session.getbulk(0, 1, varbind)),
)

for error_type, call in calls:
with self.subTest(call=call):
with self.assertRaises(error_type):
call()

def test_unknown_oid_returns_no_value(self):
varbind = netsnmp.Varbind('.1.3.6.1.2.1.1.999', '0')
values = netsnmp.snmpget(varbind, **READ_ARGS)
Expand Down
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