#19 null pointer dereference in proc_sym()

[chiba taiki]

Hi,

In ATasm 1.09, I found null pointer dereference in function proc_sym

when deal with digit number ,in some condition the following bug will occurred,
line 1611, if get_nxt_word() return NULL,(if the line look like hex:"11 10 00 00" , but not always crash, I didn't analyse deeply).

The str[0] then will result in null pointer dereference.

── source:asm.c+1612 ────
   1607        if (!addr)
   1608          skip_if();
   1609        break;
   1610      case DOT_INCLUDE:  /* .INCLUDE */
   1611        str=get_nxt_word(PARSE_NEXT_LINE);
               // str=0x00007fffffffd318  →  0x0000000000000000
 → 1612        if (str[0]=='"') {
   1613          str++;
   1614          str[strlen(str)-1]=0;
   1615        }
   1616        open_file(str);
   1617        break;
── threads ────
[#0] Id 1, Name: "atasm", stopped 0x55555555a4ee in proc_sym (), reason: SIGSEGV
─ trace ────
[#0] 0x55555555a4ee → proc_sym(sym=0x555555581a80)
[#1] 0x55555555b5fe → do_cmd(buf=0x55555556c500 <buf> "")
[#2] 0x55555555b715 → assemble(fname=0x7fffffffd600 "demo")
[#3] 0x55555555cc56 → main(argc=0x2, argv=0x7fffffffdc08)
───

==3503060==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x5563db8aa850 bp 0x7ffeda8ad000 sp 0x7ffeda8acfe0 T0)
==3503060==The signal is caused by a READ memory access.
==3503060==Hint: address points to the zero page.
    #0 0x5563db8aa84f in proc_sym /home//atasm/sasm.c:1612
    #1 0x5563db8aef4a in do_cmd /home//atasm/sasm.c:1995
    #2 0x5563db8af424 in assemble /home//atasm/sasm.c:2034
    #3 0x5563db88d341 in main /home//atasm/sasm.c:2446
    #4 0x7f5070ea80b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
    #5 0x5563db88eddd in _start (/home//atasm/satasm+0xdddd)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /atasm/src/asm.c:1612 in proc_sym
==3503060==ABORTING