diff options
Diffstat (limited to 'Objects/sliceobject.c')
| -rw-r--r-- | Objects/sliceobject.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/Objects/sliceobject.c b/Objects/sliceobject.c index 8f17fca..64be927 100644 --- a/Objects/sliceobject.c +++ b/Objects/sliceobject.c @@ -147,6 +147,13 @@ _PySlice_Unpack(PyObject *_r, "slice step cannot be zero"); return -1; } + /* Here *step might be -PY_SSIZE_T_MAX-1; in this case we replace it + * with -PY_SSIZE_T_MAX. This doesn't affect the semantics, and it + * guards against later undefined behaviour resulting from code that + * does "step = -step" as part of a slice reversal. + */ + if (*step < -PY_SSIZE_T_MAX) + *step = -PY_SSIZE_T_MAX; } if (r->start == Py_None) { |