#563 Infinite loop / null pointer access

[Jason Liang]

environment (output of uname -a: Linux fc187431a65d 4.15.0-109-generic #110-Ubuntu SMP Tue Jun 23 02:39:32 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
version: NASM version 2.16rc0
problem: run nasm with the following command
nasm -felf64 <input>

1. The crash input file provided will trigger a segmentation fault due to a null pointer dereference
2. The infinite_loop input file provided will trigger a infinite loop, and the memory consumed will keep growing util a OOM is triggered.