Fix potential NULL pointer dereference in update_symbols()

tiran · tiran · commit 45af0c83da09 · 2016-09-09T00:22:28.000+02:00
symtable_analyze() calls analyze_block() with bound=NULL. Theoretically
that NULL can be passed down to update_symbols(). update_symbols() may
deference NULL and pass it to PySet_Contains()
diff --git a/Python/symtable.c b/Python/symtable.c
@@ -652,7 +652,7 @@ update_symbols(PyObject *symbols, PyObject *scopes,
             continue;
         }
         /* Handle global symbol */
-        if (!PySet_Contains(bound, name)) {
+        if (bound && !PySet_Contains(bound, name)) {
             Py_DECREF(name);
             continue;       /* it's a global */
         }

Original file line number	Diff line number	Diff line change
`@@ -652,7 +652,7 @@ update_symbols(PyObject symbols, PyObject scopes,`
`652`	`652`	`continue;`
`653`	`653`	`}`
`654`	`654`	`/* Handle global symbol */`
`655`		`- if (!PySet_Contains(bound, name)) {`
	`655`	`+ if (bound && !PySet_Contains(bound, name)) {`
`656`	`656`	`Py_DECREF(name);`
`657`	`657`	`continue; /* it's a global */`
`658`	`658`	`}`