Fix an issue that was reported in but unrelated to the main problem of
SF bug 535905 (Evil Trashcan and GC interaction). The SETLOCAL() macro should not DECREF the local variable in-place and then store the new value; it should 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. BUGFIX CANDIDATE!
This commit is contained in:
parent
47cdf6fb6f
commit
cfbf1a33c1
|
@ -554,8 +554,16 @@ eval_frame(PyFrameObject *f)
|
||||||
/* Local variable macros */
|
/* Local variable macros */
|
||||||
|
|
||||||
#define GETLOCAL(i) (fastlocals[i])
|
#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 */
|
/* Start of code */
|
||||||
|
|
||||||
|
|
Loading…
Reference in New Issue