[python] [patch] PR python/13331
Phil Muldoon
pmuldoon@redhat.com
Mon Oct 24 13:30:00 GMT 2011
David Malcolm's GCC plug-in Python reference checker:
https://fedorahosted.org/gcc-python-plugin/
Found a path in our code that could result in a segfault. We do not
sanity check the result PyTuple_New and cascade those failures later
when we try to reference the bogus tuple. This one was a little
trickier to fix, as I had to adjust the callers to expect the failure.
For some reason, the diff of this patch is ugly, but the summary is as
follows:
- Return NULL if PyTuple_New fails.
- In the caller, check if args is NULL. If it is, do not call the
convenience function, and skip onto the exception -> error converter.
OK?
Cheers,
Phil
--
2011-10-24 Phil Muldoon <pmuldoon@redhat.com>
PR python/13331
* python/py-function.c (fnpy_call): Check 'args' is not NULL.
(convert_values_to_python): Return on Python tuple allocation
failure.
--
Index: python/py-function.c
===================================================================
RCS file: /cvs/src/src/gdb/python/py-function.c,v
retrieving revision 1.10
diff -u -r1.10 py-function.c
--- python/py-function.c 5 Aug 2011 14:24:10 -0000 1.10
+++ python/py-function.c 24 Oct 2011 13:15:38 -0000
@@ -38,6 +38,9 @@
{
int i;
PyObject *result = PyTuple_New (argc);
+
+ if (! result)
+ return NULL;
for (i = 0; i < argc; ++i)
{
@@ -59,24 +62,35 @@
void *cookie, int argc, struct value **argv)
{
struct value *value = NULL;
- PyObject *result, *callable, *args;
+ /* 'result' must be set to NULL, this initially indicates whether
+ the function was called, or not. */
+ PyObject *result = NULL;
+ PyObject *callable, *args;
struct cleanup *cleanup;
cleanup = ensure_python_env (gdbarch, language);
args = convert_values_to_python (argc, argv);
+ /* convert_values_to_python can return NULL on error. If we
+ encounter this, do not call the function, but allow the Python ->
+ error code conversion below to deal with the Python exception.
+ Note, that this is different if the function simply does not
+ have arguments. */
- callable = PyObject_GetAttrString ((PyObject *) cookie, "invoke");
- if (! callable)
+ if (args)
{
+ callable = PyObject_GetAttrString ((PyObject *) cookie, "invoke");
+ if (! callable)
+ {
+ Py_DECREF (args);
+ error (_("No method named 'invoke' in object."));
+ }
+
+ result = PyObject_Call (callable, args, NULL);
+ Py_DECREF (callable);
Py_DECREF (args);
- error (_("No method named 'invoke' in object."));
}
- result = PyObject_Call (callable, args, NULL);
- Py_DECREF (callable);
- Py_DECREF (args);
-
if (!result)
{
PyObject *ptype, *pvalue, *ptraceback;
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