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heap-buffer-overflow in /home/moonagirl/megic_afl/ok-file-formats/ok_mo.c:301 ok_mo_decode2() #6

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@zzcentury

Description

@zzcentury

Test Version

dev version, git clone https://github.com/brackeen/ok-file-formats.git

Test Program

#include <stdio.h>
#include "ok_mo.h"

int main(int _argc, char **_argv) {
    FILE *file = fopen(_argv[1], "rb");
    ok_mo *image = ok_mo_read(file);
    fclose(file);
    ok_mo_free(image);
    return 0;
}

$ gcc -o mo_decode mo_decode.c ok_mo.h ok_mo.c

Asan Debug Information

ok-file-formats git:(master) ✗ ./mo_decode-asan ./mo_out/03-heap-buffer-overflow.mo 
=================================================================
==31120==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60200000ef71 at pc 0x0000004058ae bp 0x7ffc8b9cb940 sp 0x7ffc8b9cb930
READ of size 1 at 0x60200000ef71 thread T0
    #0 0x4058ad in ok_mo_decode2 /home/moonagirl/megic_afl/ok-file-formats/ok_mo.c:301
    #1 0x4058ad in ok_mo_decode /home/moonagirl/megic_afl/ok-file-formats/ok_mo.c:96
    #2 0x4058ad in ok_mo_read /home/moonagirl/megic_afl/ok-file-formats/ok_mo.c:145
    #3 0x401074 in main /home/moonagirl/megic_afl/ok-file-formats/mo_decode.c:6
    #4 0x7f526eb0c82f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
    #5 0x4011c8 in _start (/home/moonagirl/megic_afl/ok-file-formats/mo_decode-asan+0x4011c8)

0x60200000ef71 is located 0 bytes to the right of 1-byte region [0x60200000ef70,0x60200000ef71)
allocated by thread T0 here:
    #0 0x7f526ef4e602 in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.2+0x98602)
    #1 0x40511b in ok_mo_decode2 /home/moonagirl/megic_afl/ok-file-formats/ok_mo.c:285
    #2 0x40511b in ok_mo_decode /home/moonagirl/megic_afl/ok-file-formats/ok_mo.c:96
    #3 0x40511b in ok_mo_read /home/moonagirl/megic_afl/ok-file-formats/ok_mo.c:145

SUMMARY: AddressSanitizer: heap-buffer-overflow /home/moonagirl/megic_afl/ok-file-formats/ok_mo.c:301 ok_mo_decode2
Shadow bytes around the buggy address:
  0x0c047fff9d90: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9da0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9db0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9dc0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9dd0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c047fff9de0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa[01]fa
  0x0c047fff9df0: fa fa 00 fa fa fa 01 fa fa fa 00 00 fa fa 00 00
  0x0c047fff9e00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9e10: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9e20: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9e30: 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
  Heap right redzone:      fb
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack partial redzone:   f4
  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
==31120==ABORTING

POC file

https://github.com/moonAgirl/Bugs/blob/master/ok-file-formats/2018-12-31-03-heap-buffer-overflow.mo

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