diff options
Diffstat (limited to 'Python/ceval.c')
| -rw-r--r-- | Python/ceval.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/Python/ceval.c b/Python/ceval.c index 97a734c..a93ceea 100644 --- a/Python/ceval.c +++ b/Python/ceval.c @@ -554,8 +554,16 @@ eval_frame(PyFrameObject *f) /* Local variable macros */ #define GETLOCAL(i) (fastlocals[i]) -#define SETLOCAL(i, value) do { Py_XDECREF(GETLOCAL(i)); \ - GETLOCAL(i) = value; } while (0) + +/* The SETLOCAL() macro must not DECREF the local variable in-place and + then store the new value; it must copy the old value to a temporary + value, then store the new value, and then DECREF the temporary value. + This is because it is possible that during the DECREF the frame is + accessed by other code (e.g. a __del__ method or gc.collect()) and the + variable would be pointing to already-freed memory. */ +#define SETLOCAL(i, value) do { PyObject *tmp = GETLOCAL(i); \ + GETLOCAL(i) = value; \ + Py_XDECREF(tmp); } while (0) /* Start of code */ |