A NULL pointer dereference issue in elf2dmp
Description of problem:
SIGSEGV in get_pml4e for it didn't handle NULL result properly.
Steps to reproduce:
1.launch qemu and running "gab attach -p $QEMU_PID", run "gcore" inside gdb to generate coredump
2../elf2dmp ./core.111 ./out.dmp 
3.get segemantation fault
Additional information:
![1](/uploads/39da5ed2da15b105664ee7ee05f69078/1.png)