kernel: fix buffer overflow from incorrect K_MSGQ_DEFINE definition

Without these parentheses, specifying a q_max_msgs of e.g.
`MY_DEFAULT_QUEUESIZE+1` would result in a buffer of size
(1 element + MY_DEFAULT_QUEUESIZE bytes).

This would then lead to an unbounded buffer overflow because the queue
never reaches the exact (offset by MY_DEFAULT_QUEUESIZE bytes)
`buffer_end` and just keeps writing.

Additionally, add asserts to make sure this can't happen again.

Signed-off-by: Armin Brauns <armin.brauns@embedded-solutions.at>
2 files changed