provenance tracking for memory regions

[bollu]

As requested by @pennyannn , we want to be able to ensure that reads and writes in our memory model only occur from pre-defined memory regions.

This automatically ensures that the program does not read from or write to memory locations that are outside of the permissible ones.

For an example issue that was caused without such tracking, see The OpenSSL advisory on Input buffer over-read in AES-XTS implementation on 64 bit ARM

The AES-XTS cipher decryption implementation for 64 bit ARM platform will read
past the end of the ciphertext buffer if the ciphertext size is 4 mod 5 in 16
byte blocks, e.g. 144 bytes or 1024 bytes. If the memory after the ciphertext
buffer is unmapped, this will trigger a crash which results in a denial of
service.