[2019-08-02] - Found with Honggfuzz - CVE-2019-14528

Heap-based buffer overflow in the read_literal() function, in cobc/scanner.l.

Issue can be reproduced by running:

```
cobc test03.cob
```

```
=================================================================
==4209==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x62100000d900 at pc 0x0000005cecaa bp 0x7ffc17a9ac90 sp 0x7ffc17a9ac88
WRITE of size 1 at 0x62100000d900 thread T0
    #0 0x5ceca9 in read_literal /home/fcambus/gnucobol/cobc/scanner.l:1258:15
    #1 0x5b2476 in yylex /home/fcambus/gnucobol/cobc/scanner.l:321:2
    #2 0x5510db in yyparse /home/fcambus/gnucobol/cobc/parser.c:11820:16
    #3 0x51d901 in process_translate /home/fcambus/gnucobol/cobc/cobc.c:6937:8
    #4 0x5014d7 in process_file /home/fcambus/gnucobol/cobc/cobc.c:8037:19
    #5 0x4faaaf in main /home/fcambus/gnucobol/cobc/cobc.c:8219:12
    #6 0x7fe2aadd8b6a in __libc_start_main /build/glibc-KRRWSm/glibc-2.29/csu/../csu/libc-start.c:308:16
    #7 0x41c539 in _start (/usr/local/bin/cobc+0x41c539)

0x62100000d900 is located 0 bytes to the right of 4096-byte region [0x62100000c900,0x62100000d900)
allocated by thread T0 here:
    #0 0x4c82ff in realloc /build/llvm-toolchain-8-F3l7P1/llvm-toolchain-8-8/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:165:3
    #1 0x4f7b7c in cobc_realloc /home/fcambus/gnucobol/cobc/cobc.c:1032:9
    #2 0x5ce65c in read_literal /home/fcambus/gnucobol/cobc/scanner.l:1212:17
    #3 0x5b2476 in yylex /home/fcambus/gnucobol/cobc/scanner.l:321:2
    #4 0x5510db in yyparse /home/fcambus/gnucobol/cobc/parser.c:11820:16
    #5 0x51d901 in process_translate /home/fcambus/gnucobol/cobc/cobc.c:6937:8
    #6 0x5014d7 in process_file /home/fcambus/gnucobol/cobc/cobc.c:8037:19
    #7 0x4faaaf in main /home/fcambus/gnucobol/cobc/cobc.c:8219:12
    #8 0x7fe2aadd8b6a in __libc_start_main /build/glibc-KRRWSm/glibc-2.29/csu/../csu/libc-start.c:308:16

SUMMARY: AddressSanitizer: heap-buffer-overflow /home/fcambus/gnucobol/cobc/scanner.l:1258:15 in read_literal
Shadow bytes around the buggy address:
  0x0c427fff9ad0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c427fff9ae0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c427fff9af0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c427fff9b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c427fff9b10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c427fff9b20:[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c427fff9b30: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c427fff9b40: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c427fff9b50: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c427fff9b60: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c427fff9b70: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
  Shadow gap:              cc
==4209==ABORTING
```