## Affected version 

[the latest commit](https://github.com/LibreDWG/libredwg/commit/4c210bbae04957b7d4aba55aee8dca42337f8d47) and 0.12.4

## What's the problem?


A heap buffer overflow was discovered in dwg_section_wtype in dwg.c:1663.

ASAN report:

```
./dwgread ./tests_64206
=================================================================
==9487==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffd7f8d5f78 at pc 0x0000004ce5e4 bp 0x7ffd7f8d5f30 sp 0x7ffd7f8d5f28
WRITE of size 1 at 0x7ffd7f8d5f78 thread T0
    #0 0x4ce5e3 in dwg_section_wtype /root/fuzz/libredwg/src/dwg.c:1663:17
    #1 0xc85dfc in read_sections_map /root/fuzz/libredwg/src/decode_r2007.c:966:23
    #2 0xc83bd6 in read_r2007_meta_data /root/fuzz/libredwg/src/decode_r2007.c:2367:18
    #3 0x4f9fcc in decode_R2007 /root/fuzz/libredwg/src/decode.c:3836:11
    #4 0x4e49ab in dwg_decode /root/fuzz/libredwg/src/decode.c:248:29
    #5 0x4c75cc in dwg_read_file /root/fuzz/libredwg/src/dwg.c:254:11
    #6 0x4c5d47 in main /root/fuzz/libredwg/programs/dwgread.c
    #7 0x7f3d92d0483f in __libc_start_main /build/glibc-S7Ft5T/glibc-2.23/csu/../csu/libc-start.c:291
    #8 0x41ba58 in _start (/root/fuzz/pocs/dwgread+0x41ba58)

Address 0x7ffd7f8d5f78 is located in stack of thread T0 at offset 56 in frame
    #0 0x4ce3ef in dwg_section_wtype /root/fuzz/libredwg/src/dwg.c:1652

  This frame has 1 object(s):
    [32, 56) 'name' (line 1654) <== Memory access at offset 56 overflows this variable
HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow /root/fuzz/libredwg/src/dwg.c:1663:17 in dwg_section_wtype
Shadow bytes around the buggy address:
  0x10002ff12b90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002ff12ba0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002ff12bb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002ff12bc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002ff12bd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x10002ff12be0: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00[f3]
  0x10002ff12bf0: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002ff12c00: 00 00 00 00 f1 f1 f1 f1 00 f3 f3 f3 00 00 00 00
  0x10002ff12c10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002ff12c20: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00
  0x10002ff12c30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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
==9487==ABORTING
```


## Compile command

```
CC="clang" CFLAGS="-O1 -g -fsanitize=address" ./configure --enable-release --disable-shared && make
```

## How can we reproduce the issue?

```
unzip tests_64206.zip
dwgread ./tests_64206
```
POC file :  [tests_64206.zip](https://github.com/LibreDWG/libredwg/files/6606924/tests_64206.zip)

stack-buffer-overflow in dwg_section_wtype in dwg.c:1663
This is a GitHub Issue
repo:libredwg
owner:LibreDWG
Title : stack-buffer-overflow in dwg_section_wtype in dwg.c:1663
Issue date:

--- start body ---
## Affected version 

[the latest commit](https://github.com/LibreDWG/libredwg/commit/4c210bbae04957b7d4aba55aee8dca42337f8d47) and 0.12.4

## What's the problem?


A heap buffer overflow was discovered in dwg_section_wtype in dwg.c:1663.

ASAN report:

```
./dwgread ./tests_64206
=================================================================
==9487==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffd7f8d5f78 at pc 0x0000004ce5e4 bp 0x7ffd7f8d5f30 sp 0x7ffd7f8d5f28
WRITE of size 1 at 0x7ffd7f8d5f78 thread T0
    #0 0x4ce5e3 in dwg_section_wtype /root/fuzz/libredwg/src/dwg.c:1663:17
    #1 0xc85dfc in read_sections_map /root/fuzz/libredwg/src/decode_r2007.c:966:23
    #2 0xc83bd6 in read_r2007_meta_data /root/fuzz/libredwg/src/decode_r2007.c:2367:18
    #3 0x4f9fcc in decode_R2007 /root/fuzz/libredwg/src/decode.c:3836:11
    #4 0x4e49ab in dwg_decode /root/fuzz/libredwg/src/decode.c:248:29
    #5 0x4c75cc in dwg_read_file /root/fuzz/libredwg/src/dwg.c:254:11
    #6 0x4c5d47 in main /root/fuzz/libredwg/programs/dwgread.c
    #7 0x7f3d92d0483f in __libc_start_main /build/glibc-S7Ft5T/glibc-2.23/csu/../csu/libc-start.c:291
    #8 0x41ba58 in _start (/root/fuzz/pocs/dwgread+0x41ba58)

Address 0x7ffd7f8d5f78 is located in stack of thread T0 at offset 56 in frame
    #0 0x4ce3ef in dwg_section_wtype /root/fuzz/libredwg/src/dwg.c:1652

  This frame has 1 object(s):
    [32, 56) 'name' (line 1654) <== Memory access at offset 56 overflows this variable
HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow /root/fuzz/libredwg/src/dwg.c:1663:17 in dwg_section_wtype
Shadow bytes around the buggy address:
  0x10002ff12b90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002ff12ba0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002ff12bb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002ff12bc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002ff12bd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x10002ff12be0: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00[f3]
  0x10002ff12bf0: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002ff12c00: 00 00 00 00 f1 f1 f1 f1 00 f3 f3 f3 00 00 00 00
  0x10002ff12c10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002ff12c20: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00
  0x10002ff12c30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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
==9487==ABORTING
```


## Compile command

```
CC="clang" CFLAGS="-O1 -g -fsanitize=address" ./configure --enable-release --disable-shared && make
```

## How can we reproduce the issue?

```
unzip tests_64206.zip
dwgread ./tests_64206
```
POC file :  [tests_64206.zip](https://github.com/LibreDWG/libredwg/files/6606924/tests_64206.zip)

--- end body ---
