ShmDispatcher crash by race condition

[Junxia0Wang]

Describe the bug
ShmDispatcher crash by race condition

To Reproduce
Steps to reproduce the behavior:

1. Message enqueue to shm dispatcher
2. Segment remap
3. ShmDispatcher start to process message
4. Use overdue idx to bounds check for new segment
5. Crash

To resolve
Bounds check should before remap call

[Junxia0Wang]

sorry, bounds check should after remap call