py/objslice: Validate that the argument to indices() is an integer.

Otherwise passing in a non-integer can lead to an invalid memory access.

Thanks to Junwha Hong and Wonil Jang @S2Lab, UNIST for finding the issue.

Fixes issue #13007.

Signed-off-by: Damien George <damien@micropython.org>

py/objslice.c

@@ -54,7 +54,7 @@ STATIC mp_obj_t slice_unary_op(mp_unary_op_t op, mp_obj_t o_in) {
 
 #if MICROPY_PY_BUILTINS_SLICE_INDICES
 STATIC mp_obj_t slice_indices(mp_obj_t self_in, mp_obj_t length_obj) {
-    mp_int_t length = mp_obj_int_get_checked(length_obj);
+    mp_int_t length = mp_obj_get_int(length_obj);
     mp_bound_slice_t bound_indices;
     mp_obj_slice_indices(self_in, length, &bound_indices);
 

tests/basics/slice_indices.py

@@ -25,3 +25,8 @@ print(A()[2:7:2].indices(5))
 print(A()[2:7:-2].indices(5))
 print(A()[7:2:2].indices(5))
 print(A()[7:2:-2].indices(5))
+
+try:
+    print(A()[::].indices(None))
+except TypeError:
+    print("TypeError")