Project: libredwg (libredwg/libredwg), language: c++
Vulnerability instance: libredwg.cve-2020-21831
Sanitizer: address

================= Bug Report (1/1) ==================
## Source: GitHub Issue
## URL: https://github.com/LibreDWG/libredwg/issues/188#issuecomment-574493267
## Description:
Issue: LibreDWG/libredwg#188
Title: Several bugs found by fuzzing
Referenced comment by linhlhq on 2020-01-15 04:42:20+00:00:

**9.heap-buffer-overflow in read_2004_section_handles ../../src/decode.c:2637**
POC:https://github.com/linhlhq/research/blob/master/PoCs/libreDWG_4c26d37/id:000168%2Csig:06%2Csrc:001038%2Cop:havoc%2Crep:4

```
=================================================================
==21207==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x629000004f20 at pc 0x7fbe8d213733 bp 0x7ffdd9fa0a80 sp 0x7ffdd9fa0228
READ of size 29696 at 0x629000004f20 thread T0
    #0 0x7fbe8d213732  (/usr/lib/x86_64-linux-gnu/libasan.so.4+0x79732)
    #1 0x558f0e7517b6 in memcpy /usr/include/x86_64-linux-gnu/bits/string_fortified.h:34
    #2 0x558f0e7517b6 in read_2004_compressed_section ../../src/decode.c:2417
    #3 0x558f0ed15353 in read_2004_section_handles ../../src/decode.c:2637
    #4 0x558f0ed15353 in decode_R2004 ../../src/decode.c:3354
    #5 0x558f0ed2708d in dwg_decode ../../src/decode.c:246
    #6 0x558f0e6b9fae in dwg_read_file ../../src/dwg.c:211
    #7 0x558f0e6b89d0 in get_bmp ../../programs/dwgbmp.c:111
    #8 0x558f0e6b8066 in main ../../programs/dwgbmp.c:280
    #9 0x7fbe8ca2cb96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b96)
    #10 0x558f0e6b86c9 in _start (/home/user/linhlhq/libredwg/asan_build/programs/dwgbmp+0x28f6c9)

0x629000004f20 is located 0 bytes to the right of 19744-byte region [0x629000000200,0x629000004f20)
allocated by thread T0 here:
    #0 0x7fbe8d278d38 in __interceptor_calloc (/usr/lib/x86_64-linux-gnu/libasan.so.4+0xded38)
    #1 0x558f0e6b9f41 in dat_read_file ../../src/dwg.c:74
    #2 0x558f0e6b9f41 in dwg_read_file ../../src/dwg.c:204

SUMMARY: AddressSanitizer: heap-buffer-overflow (/usr/lib/x86_64-linux-gnu/libasan.so.4+0x79732)
Shadow bytes around the buggy address:
  0x0c527fff8990: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c527fff89a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c527fff89b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c527fff89c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c527fff89d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c527fff89e0: 00 00 00 00[fa]fa fa fa fa fa fa fa fa fa fa fa
  0x0c527fff89f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c527fff8a00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c527fff8a10: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c527fff8a20: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c527fff8a30: 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
==21207==ABORTING
```

Build script:
#!/bin/bash -eu
# Minimized build script with only core build commands
set -eu
sh ./autogen.sh
./configure --disable-shared
make -j$(nproc)

Dockerfile:
FROM hwiwonlee/secb.base:latest
RUN apt-get update && apt-get install -y autoconf libtool texinfo
RUN git clone https://github.com/libredwg/libredwg libredwg
RUN git -C libredwg checkout d5a51c01023d5585ddf3dd17c83dbb3c81efc97e
WORKDIR $SRC/libredwg
COPY build.sh $SRC/

Additional files:
filename: fuzz_dwg_decode.options
content: [libfuzzer]
detect_leaks=0