extmod/machine_mem: Only allow integers in machine.memX subscript.

Prior to this change machine.mem32['foo'] (or using any other non-integer
subscript) could result in a fault due to 'foo' being interpreted as an
integer.  And when writing code it's hard to tell if the fault is due to a
bad subscript type, or an integer subscript that specifies an invalid
memory address.

The type of the object used in the subscript is now tested to be an
integer by using mp_obj_get_int_truncated instead of
mp_obj_int_get_truncated.  The performance hit of this change is minimal,
and machine.memX objects are more for convenience than performance (there
are many other ways to read/write memory in a faster way),

Fixes issue #6588.

1 files changed, 20 insertions, 0 deletions

diff --git a/tests/extmod/machine1.py b/tests/extmod/machine1.py
index 6ff38cc051..0c7f8122f4 100644
--- a/tests/extmod/machine1.py
+++ b/tests/extmod/machine1.py
@@ -26,3 +26,23 @@ try:
     del machine.mem8[0]
 except TypeError:
     print("TypeError")
+
+try:
+    machine.mem8[0:1]
+except TypeError:
+    print("TypeError")
+
+try:
+    machine.mem8[0:1] = 10
+except TypeError:
+    print("TypeError")
+
+try:
+    machine.mem8["hello"]
+except TypeError:
+    print("TypeError")
+
+try:
+    machine.mem8["hello"] = 10
+except TypeError:
+    print("TypeError")