[Nasm-bugs] [Bug 3392839] New: global-buffer-overflow in nasm (dbgdbg_typevalue)

[noreply-nasm at dev.nasm.us]

https://bugzilla.nasm.us/show_bug.cgi?id=3392839

            Bug ID: 3392839
           Summary: global-buffer-overflow in nasm (dbgdbg_typevalue)
           Product: NASM
           Version: 2.17 (development)
          Hardware: All
                OS: All
            Status: OPEN
          Severity: normal
          Priority: Medium
         Component: Assembler
          Assignee: nobody at nasm.us
          Reporter: youngseok.main at gmail.com
                CC: chang.seok.bae at intel.com, gorcunov at gmail.com,
                    hpa at zytor.com, nasm-bugs at nasm.us
     Obtained from: Built from git using configure

Hello,

Our fuzzer found a global-buffer-overflow bug in nasm.

Command Input:
nasm . -fdbg -g --Before "Do-p;

Stack Trace:
==18257==ERROR: AddressSanitizer: global-buffer-overflow on address
0x5555557fe168 at pc 0x55555571c29e bp 0x7fffffffdb60 sp 0x7fffffffdb50
READ of size 8 at 0x5555557fe168 thread T0
    #0 0x55555571c29d in dbgdbg_typevalue output/outdbg.c:459
    #1 0x555555699355 in debug_set_db_type asm/assemble.c:1017
    #2 0x555555699f0d in insn_size asm/assemble.c:1140
    #3 0x555555685ee5 in process_insn asm/nasm.c:1595
    #4 0x55555568694a in assemble_file asm/nasm.c:1734
    #5 0x555555681f50 in main asm/nasm.c:716
    #6 0x7ffff6a48c86 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x21c86)
    #7 0x55555567f699 in _start
(/home/youngseok/latest-subjects/nasm/nasm+0x12b

Environment:
OS: Ubuntu 18.04
gcc: 7.5.0
nasm: 2.17rc0 (Git master branch, a916e4127b2eaa3bf40bddf3de9b0ceefc0d98a)

Any comments related to the crash are welcome. Since we are developing a new
fuzzing technique, it would be very helpful for our work.

Thank you.

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