Steps to reproduce:
file: plug-ins/pygimp/pygimp-tile.c
function: pr_subscript(PyGimpPixelRgn *self, PyObject *key)

Local variables "x1, y1, x2, y2, xs, ys" are of type "int" (4-byte) but they have to be of type "Py_ssize_t" (8-byte on 64-bit platforms). Because when they are only 4-byte ints then the function PySlice_GetIndices incorectly overwrites them.

E.g.

rgn = drawable.get_pixel_rgn(0, 0,
                        drawable.width, drawable.height,
                        False, False)
pixels = rgn[0:drawable.width, 0:drawable.height] # this will fail

Stack trace:


Other information: