# Description
heap-buffer-overflow in gf_fwrite at utils/os_file.c:1657

# Version
```
git log
commit 7edc40feef23efd8c9948292d269eae76fa475af (HEAD -> master, origin/master, origin/HEAD)
Author: jeanlf <jeanlf@gpac.io>
Date:   Thu Oct 12 16:58:53 2023 +0200

./bin/gcc/MP4Box -version
MP4Box - GPAC version 2.3-DEV-rev588-g7edc40fee-master
(c) 2000-2023 Telecom Paris distributed under LGPL v2.1+ - http://gpac.io
```
# POC 
https://github.com/Janette88/test_pocs/blob/main/hbo16

# Reproduce
```
./bin/gcc/MP4Box -dash 1000 /home/fuzz/crashes/hbo16


[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
=================================================================
==60235==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6020000025d1 at pc 0x7ffff75ed1bd bp 0x7ffffffec720 sp 0x7ffffffebec8
READ of size 53248 at 0x6020000025d1 thread T0
    #0 0x7ffff75ed1bc in __interceptor_fwrite ../../../../src/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:1103
    #1 0x7ffff3ba5226 in gf_fwrite utils/os_file.c:1657
    #2 0x7ffff4655f98 in swf_def_bits_jpeg scene_manager/swf_parse.c:2087
    #3 0x7ffff46576d4 in swf_process_tag scene_manager/swf_parse.c:2374
    #4 0x7ffff46576d4 in swf_parse_tag scene_manager/swf_parse.c:2405
    #5 0x7ffff4d55ed9 in gf_text_process_swf filters/load_text.c:2550
    #6 0x7ffff4d55ed9 in gf_text_process_swf filters/load_text.c:2527
    #7 0x7ffff4d6b4f3 in txtin_process filters/load_text.c:4015
    #8 0x7ffff4a5d4ae in gf_filter_process_task filter_core/filter.c:2971
    #9 0x7ffff4a2ab11 in gf_fs_thread_proc filter_core/filter_session.c:2105
    #10 0x7ffff4a2f8b6 in gf_fs_run filter_core/filter_session.c:2405
    #11 0x7ffff43bc0bd in gf_dasher_process media_tools/dash_segmenter.c:1236
    #12 0x555555621d26 in do_dash /home/fuzz/gpac/applications/mp4box/mp4box.c:4831
    #13 0x555555621d26 in mp4box_main /home/fuzz/gpac/applications/mp4box/mp4box.c:6245
    #14 0x7ffff164c082 in __libc_start_main ../csu/libc-start.c:308
    #15 0x5555555fa05d in _start (/home/fuzz/gpac/bin/gcc/MP4Box+0xa605d)

0x6020000025d1 is located 0 bytes to the right of 1-byte region [0x6020000025d0,0x6020000025d1)
allocated by thread T0 here:
    #0 0x7ffff7690808 in __interceptor_malloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cc:144
    #1 0x7ffff465a345 in swf_def_hdr_jpeg scene_manager/swf_parse.c:2044
    #2 0x7ffff465a345 in swf_process_tag scene_manager/swf_parse.c:2372
    #3 0x7ffff465a345 in swf_parse_tag scene_manager/swf_parse.c:2405
    #4 0x7ffff4d55ed9 in gf_text_process_swf filters/load_text.c:2550
    #5 0x7ffff4d55ed9 in gf_text_process_swf filters/load_text.c:2527
    #6 0x7ffff4d6b4f3 in txtin_process filters/load_text.c:4015
    #7 0x7ffff4a5d4ae in gf_filter_process_task filter_core/filter.c:2971
    #8 0x7ffff4a2ab11 in gf_fs_thread_proc filter_core/filter_session.c:2105
    #9 0x7ffff4a2f8b6 in gf_fs_run filter_core/filter_session.c:2405
    #10 0x7ffff43bc0bd in gf_dasher_process media_tools/dash_segmenter.c:1236
    #11 0x555555621d26 in do_dash /home/fuzz/gpac/applications/mp4box/mp4box.c:4831
    #12 0x555555621d26 in mp4box_main /home/fuzz/gpac/applications/mp4box/mp4box.c:6245
    #13 0x7ffff164c082 in __libc_start_main ../csu/libc-start.c:308

SUMMARY: AddressSanitizer: heap-buffer-overflow ../../../../src/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:1103 in __interceptor_fwrite
Shadow bytes around the buggy address:
  0x0c047fff8460: fa fa fd fa fa fa 00 00 fa fa 00 00 fa fa fd fa
  0x0c047fff8470: fa fa fd fd fa fa fd fa fa fa 00 07 fa fa 00 07
  0x0c047fff8480: fa fa 04 fa fa fa 00 05 fa fa 00 00 fa fa 00 00
  0x0c047fff8490: fa fa fd fa fa fa fd fd fa fa fd fd fa fa fd fd
  0x0c047fff84a0: fa fa 00 00 fa fa 00 00 fa fa 00 00 fa fa 00 00
=>0x0c047fff84b0: fa fa 00 00 fa fa 00 00 fa fa[01]fa fa fa fa fa
  0x0c047fff84c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff84d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff84e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff84f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8500: 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
==60235==ABORTING
```
# Impact

This vulnerability allows a remote attacker to cause a denial of service or even arbitrary code execution on an affected gpac MP4Box. Exploiting this vulnerability requires user interaction, as the target must access a malicious page or open a malicious file.

# Credit
Janette88 (Jq Wang)
heap-buffer-overflow in gf_fwrite at utils/os_file.c:1657
This is a GitHub Issue
repo:gpac
owner:gpac
Title : heap-buffer-overflow in gf_fwrite at utils/os_file.c:1657
Issue date:

--- start body ---
# Description
heap-buffer-overflow in gf_fwrite at utils/os_file.c:1657

# Version
```
git log
commit 7edc40feef23efd8c9948292d269eae76fa475af (HEAD -> master, origin/master, origin/HEAD)
Author: jeanlf <jeanlf@gpac.io>
Date:   Thu Oct 12 16:58:53 2023 +0200

./bin/gcc/MP4Box -version
MP4Box - GPAC version 2.3-DEV-rev588-g7edc40fee-master
(c) 2000-2023 Telecom Paris distributed under LGPL v2.1+ - http://gpac.io
```
# POC 
https://github.com/Janette88/test_pocs/blob/main/hbo16

# Reproduce
```
./bin/gcc/MP4Box -dash 1000 /home/fuzz/crashes/hbo16


[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
[SWF Parsing] tag PlaceObject over-read of 4 bytes (size 1) (frame 1)
=================================================================
==60235==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6020000025d1 at pc 0x7ffff75ed1bd bp 0x7ffffffec720 sp 0x7ffffffebec8
READ of size 53248 at 0x6020000025d1 thread T0
    #0 0x7ffff75ed1bc in __interceptor_fwrite ../../../../src/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:1103
    #1 0x7ffff3ba5226 in gf_fwrite utils/os_file.c:1657
    #2 0x7ffff4655f98 in swf_def_bits_jpeg scene_manager/swf_parse.c:2087
    #3 0x7ffff46576d4 in swf_process_tag scene_manager/swf_parse.c:2374
    #4 0x7ffff46576d4 in swf_parse_tag scene_manager/swf_parse.c:2405
    #5 0x7ffff4d55ed9 in gf_text_process_swf filters/load_text.c:2550
    #6 0x7ffff4d55ed9 in gf_text_process_swf filters/load_text.c:2527
    #7 0x7ffff4d6b4f3 in txtin_process filters/load_text.c:4015
    #8 0x7ffff4a5d4ae in gf_filter_process_task filter_core/filter.c:2971
    #9 0x7ffff4a2ab11 in gf_fs_thread_proc filter_core/filter_session.c:2105
    #10 0x7ffff4a2f8b6 in gf_fs_run filter_core/filter_session.c:2405
    #11 0x7ffff43bc0bd in gf_dasher_process media_tools/dash_segmenter.c:1236
    #12 0x555555621d26 in do_dash /home/fuzz/gpac/applications/mp4box/mp4box.c:4831
    #13 0x555555621d26 in mp4box_main /home/fuzz/gpac/applications/mp4box/mp4box.c:6245
    #14 0x7ffff164c082 in __libc_start_main ../csu/libc-start.c:308
    #15 0x5555555fa05d in _start (/home/fuzz/gpac/bin/gcc/MP4Box+0xa605d)

0x6020000025d1 is located 0 bytes to the right of 1-byte region [0x6020000025d0,0x6020000025d1)
allocated by thread T0 here:
    #0 0x7ffff7690808 in __interceptor_malloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cc:144
    #1 0x7ffff465a345 in swf_def_hdr_jpeg scene_manager/swf_parse.c:2044
    #2 0x7ffff465a345 in swf_process_tag scene_manager/swf_parse.c:2372
    #3 0x7ffff465a345 in swf_parse_tag scene_manager/swf_parse.c:2405
    #4 0x7ffff4d55ed9 in gf_text_process_swf filters/load_text.c:2550
    #5 0x7ffff4d55ed9 in gf_text_process_swf filters/load_text.c:2527
    #6 0x7ffff4d6b4f3 in txtin_process filters/load_text.c:4015
    #7 0x7ffff4a5d4ae in gf_filter_process_task filter_core/filter.c:2971
    #8 0x7ffff4a2ab11 in gf_fs_thread_proc filter_core/filter_session.c:2105
    #9 0x7ffff4a2f8b6 in gf_fs_run filter_core/filter_session.c:2405
    #10 0x7ffff43bc0bd in gf_dasher_process media_tools/dash_segmenter.c:1236
    #11 0x555555621d26 in do_dash /home/fuzz/gpac/applications/mp4box/mp4box.c:4831
    #12 0x555555621d26 in mp4box_main /home/fuzz/gpac/applications/mp4box/mp4box.c:6245
    #13 0x7ffff164c082 in __libc_start_main ../csu/libc-start.c:308

SUMMARY: AddressSanitizer: heap-buffer-overflow ../../../../src/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:1103 in __interceptor_fwrite
Shadow bytes around the buggy address:
  0x0c047fff8460: fa fa fd fa fa fa 00 00 fa fa 00 00 fa fa fd fa
  0x0c047fff8470: fa fa fd fd fa fa fd fa fa fa 00 07 fa fa 00 07
  0x0c047fff8480: fa fa 04 fa fa fa 00 05 fa fa 00 00 fa fa 00 00
  0x0c047fff8490: fa fa fd fa fa fa fd fd fa fa fd fd fa fa fd fd
  0x0c047fff84a0: fa fa 00 00 fa fa 00 00 fa fa 00 00 fa fa 00 00
=>0x0c047fff84b0: fa fa 00 00 fa fa 00 00 fa fa[01]fa fa fa fa fa
  0x0c047fff84c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff84d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff84e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff84f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8500: 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
==60235==ABORTING
```
# Impact

This vulnerability allows a remote attacker to cause a denial of service or even arbitrary code execution on an affected gpac MP4Box. Exploiting this vulnerability requires user interaction, as the target must access a malicious page or open a malicious file.

# Credit
Janette88 (Jq Wang)
--- end body ---
