Created attachment 411756 [details] poc Hi, I found a stack-overflow in scan at stdscan.c:131 It is triggered in nasm version 2.15. NASM version 2.15rc0-20191023 compiled on Dec 9 2019 Please run following command $ nasm -o /dev/null -f win64 $PoC Here's ASAN log ==303==ERROR: AddressSanitizer: stack-overflow on address 0x7fffe3d12ed8 (pc 0x0000004d7a4c bp 0x7fffe3d13750 sp 0x7fffe3d12ee0 T0) #0 0x4d7a4b in __asan_memset (/mnt/hda2/suhwan/BUG_AFL/ezxml_fuzzing/nasm+0x4d7a4b) #1 0x6d7461 in stdscan /home/suhwan/project/program/nasm-2.15rc0-20191023/asm/stdscan.c:131:5 #2 0x6bd797 in scan /home/suhwan/project/program/nasm-2.15rc0-20191023/asm/eval.c:263:17 #3 0x6bd797 in expr6 /home/suhwan/project/program/nasm-2.15rc0-20191023/asm/eval.c:838
Doesn't trigger in nasm-2.15.xx series.
To be precise in nasm-2.15.04rc5-4-g51e23ac7