Created attachment 411857 [details] the POC file. Hi, developers of NASM: I tested the binary nasm and a SEGV crash incurred. The version of NASM is the latest (the newest master branch in github (https://github.com/netwide-assembler/nasm.git), version: NASM version 2.16rc0 compiled on Sep 20 2022) and the operation system is Ubuntu 18.04.6 LTS (docker). The following is the details. Bug root@81be2c9c39ff:/# ./../nasm/nasm -f ieee poc_nasm poc_nasm:1: warning: label alone on a line without a colon might be in error [-w+label-orphan] AddressSanitizer:DEADLYSIGNAL ================================================================= ==670171==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000008 (pc 0x00000056e1fb bp 0x7fff0dd490a0 sp 0x7fff0dd48940 T0) ==670171==The signal is caused by a READ memory access. ==670171==Hint: address points to the zero page. #0 0x56e1fb in ieee_write_file (/nasm/nasm+0x56e1fb) #1 0x56d85c in ieee_cleanup (/nasm/nasm+0x56d85c) #2 0x4e629d in main (/nasm/nasm+0x4e629d) #3 0x7f9395de0c86 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21c86) #4 0x41d119 in _start (/nasm/nasm+0x41d119) AddressSanitizer can not provide additional info. SUMMARY: AddressSanitizer: SEGV (/nasm/nasm+0x56e1fb) in ieee_write_file ==670171==ABORTING I uploaded the POC in the attachment. Thank you for your time! Credit Xudong Cao (NCNIPC of China) Han Zheng (NCNIPC of China, Hexhive)