## Description
There is a heap-use-after-free detected by AddressSanitizer

## System info
```
Ubuntu 20.04.2 LTS
clang version 12.0.0-++20210402082642+04ba60cfe598-1~exp1~20210402063359.71
MP4Box - GPAC version 1.1.0-DEV-rev1671-g0cd19f4db-master
```

## Build command
```
./configure --static-mp4box --prefix=`realpath ./install` --enable-sanitizer --cc=clang --cxx=clang++
```

## crash command
MP4Box -frag 0 -out /dev/null poc_file

## Pocs
[poc.zip](https://github.com/gpac/gpac/files/7950853/poc.zip)

## Crash output
poc_41.mp4

```
==19187==ERROR: AddressSanitizer: heap-use-after-free on address 0x603000001b17 at pc 0x0000010140cf bp 0x7ffd6975cff0 sp 0x7ffd6975cfe8
READ of size 1 at 0x603000001b17 thread T0
    #0 0x10140ce in mp4_mux_cenc_update /programs/mp4box/builds/build3/src/filters/mux_isom.c:3762:21
    #1 0x1017fdb in mp4_mux_process_sample /programs/mp4box/builds/build3/src/filters/mux_isom.c:4108:8
    #2 0x1009758 in mp4_mux_process_fragmented /programs/mp4box/builds/build3/src/filters/mux_isom.c:5599:8
    #3 0x10029a1 in mp4_mux_process /programs/mp4box/builds/build3/src/filters/mux_isom.c:6029:14
    #4 0xd8d4e9 in gf_filter_process_task /programs/mp4box/builds/build3/src/filter_core/filter.c:2515:7
    #5 0xd647ef in gf_fs_thread_proc /programs/mp4box/builds/build3/src/filter_core/filter_session.c:1756:3
    #6 0xd63523 in gf_fs_run /programs/mp4box/builds/build3/src/filter_core/filter_session.c:2000:2
    #7 0xaa99ff in gf_media_fragment_file /programs/mp4box/builds/build3/src/media_tools/isom_tools.c:3816:6
    #8 0x4ebaff in mp4boxMain /programs/mp4box/builds/build3/applications/mp4box/main.c:6455:7
    #9 0x7f9d091e20b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
    #10 0x41ea6d in _start (/programs/mp4box/builds/build3/bin/gcc/MP4Box+0x41ea6d)

0x603000001b17 is located 7 bytes inside of 23-byte region [0x603000001b10,0x603000001b27)
freed by thread T0 here:
    #0 0x499a62 in free (/programs/mp4box/builds/build3/bin/gcc/MP4Box+0x499a62)
    #1 0xa5e0b8 in gf_odf_avc_cfg_del /programs/mp4box/builds/build3/src/odf/descriptors.c:482:17
    #2 0x892f2e in avcc_box_del /programs/mp4box/builds/build3/src/isomedia/avc_ext.c:2728:19
    #3 0x8d76d4 in gf_isom_box_del /programs/mp4box/builds/build3/src/isomedia/box_funcs.c:1806:3
    #4 0x998f8b in gf_isom_update_sample_description_from_template /programs/mp4box/builds/build3/src/isomedia/isom_write.c:7789:4
    #5 0x1029564 in mp4_mux_setup_pid /programs/mp4box/builds/build3/src/filters/mux_isom.c:3102:4
    #6 0xd05416 in gf_filter_pid_configure /programs/mp4box/builds/build3/src/filter_core/filter_pid.c:752:6
    #7 0xd0b67f in gf_filter_pid_get_packet /programs/mp4box/builds/build3/src/filter_core/filter_pid.c:5612:8
    #8 0x1001b28 in mp4_mux_config_timing /programs/mp4box/builds/build3/src/filters/mux_isom.c:5805:9
    #9 0x1001b28 in mp4_mux_process /programs/mp4box/builds/build3/src/filters/mux_isom.c:6019:3
    #10 0xd8d4e9 in gf_filter_process_task /programs/mp4box/builds/build3/src/filter_core/filter.c:2515:7
    #11 0xd647ef in gf_fs_thread_proc /programs/mp4box/builds/build3/src/filter_core/filter_session.c:1756:3
    #12 0xd63523 in gf_fs_run /programs/mp4box/builds/build3/src/filter_core/filter_session.c:2000:2
    #13 0xaa99ff in gf_media_fragment_file /programs/mp4box/builds/build3/src/media_tools/isom_tools.c:3816:6
    #14 0x4ebaff in mp4boxMain /programs/mp4box/builds/build3/applications/mp4box/main.c:6455:7
    #15 0x7f9d091e20b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)

previously allocated by thread T0 here:
    #0 0x499ccd in malloc (/programs/mp4box/builds/build3/bin/gcc/MP4Box+0x499ccd)
    #1 0x8934fa in avcc_box_read /programs/mp4box/builds/build3/src/isomedia/avc_ext.c:2773:22
    #2 0x8d6e8d in gf_isom_box_parse_ex /programs/mp4box/builds/build3/src/isomedia/box_funcs.c:264:14
    #3 0x8d923d in gf_isom_box_array_read_ex /programs/mp4box/builds/build3/src/isomedia/box_funcs.c:1719:7
    #4 0x1584e5a in video_sample_entry_box_read /programs/mp4box/builds/build3/src/isomedia/box_code_base.c:4304:6
    #5 0x8d6e8d in gf_isom_box_parse_ex /programs/mp4box/builds/build3/src/isomedia/box_funcs.c:264:14
    #6 0x998ce2 in gf_isom_update_sample_description_from_template /programs/mp4box/builds/build3/src/isomedia/isom_write.c:7756:6
    #7 0x1029564 in mp4_mux_setup_pid /programs/mp4box/builds/build3/src/filters/mux_isom.c:3102:4
    #8 0xd05416 in gf_filter_pid_configure /programs/mp4box/builds/build3/src/filter_core/filter_pid.c:752:6
    #9 0xd0b67f in gf_filter_pid_get_packet /programs/mp4box/builds/build3/src/filter_core/filter_pid.c:5612:8
    #10 0x1001b28 in mp4_mux_config_timing /programs/mp4box/builds/build3/src/filters/mux_isom.c:5805:9
    #11 0x1001b28 in mp4_mux_process /programs/mp4box/builds/build3/src/filters/mux_isom.c:6019:3
    #12 0xd8d4e9 in gf_filter_process_task /programs/mp4box/builds/build3/src/filter_core/filter.c:2515:7
    #13 0xd647ef in gf_fs_thread_proc /programs/mp4box/builds/build3/src/filter_core/filter_session.c:1756:3
    #14 0xd63523 in gf_fs_run /programs/mp4box/builds/build3/src/filter_core/filter_session.c:2000:2
    #15 0xaa99ff in gf_media_fragment_file /programs/mp4box/builds/build3/src/media_tools/isom_tools.c:3816:6
    #16 0x4ebaff in mp4boxMain /programs/mp4box/builds/build3/applications/mp4box/main.c:6455:7
    #17 0x7f9d091e20b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)

SUMMARY: AddressSanitizer: heap-use-after-free /programs/mp4box/builds/build3/src/filters/mux_isom.c:3762:21 in mp4_mux_cenc_update
Shadow bytes around the buggy address:
  0x0c067fff8310: fd fa fa fa fd fd fd fa fa fa 00 00 00 00 fa fa
  0x0c067fff8320: 00 00 00 06 fa fa 00 00 00 00 fa fa 00 00 04 fa
  0x0c067fff8330: fa fa 00 00 00 00 fa fa 00 00 00 06 fa fa 00 00
  0x0c067fff8340: 00 fa fa fa 00 00 00 00 fa fa 00 00 00 fa fa fa
  0x0c067fff8350: 00 00 00 00 fa fa 00 00 00 fa fa fa fd fd fd fa
=>0x0c067fff8360: fa fa[fd]fd fd fa fa fa fd fd fd fa fa fa fd fd
  0x0c067fff8370: fd fa fa fa fd fd fd fa fa fa fd fd fd fa fa fa
  0x0c067fff8380: 00 00 00 fa fa fa fd fd fd fa fa fa 00 00 00 fa
  0x0c067fff8390: fa fa 00 00 00 00 fa fa 00 00 00 06 fa fa fd fd
  0x0c067fff83a0: fd fa fa fa fd fd fd fd fa fa 00 00 00 00 fa fa
  0x0c067fff83b0: 00 00 00 fa fa fa fd fd fd fa fa fa fd fd fd fd
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
==19187==ABORTING
```
There is a heap-use-after-free detected by AddressSanitizer
This is a GitHub Issue
repo:gpac
owner:gpac
Title : There is a heap-use-after-free detected by AddressSanitizer
Issue date:

--- start body ---
## Description
There is a heap-use-after-free detected by AddressSanitizer

## System info
```
Ubuntu 20.04.2 LTS
clang version 12.0.0-++20210402082642+04ba60cfe598-1~exp1~20210402063359.71
MP4Box - GPAC version 1.1.0-DEV-rev1671-g0cd19f4db-master
```

## Build command
```
./configure --static-mp4box --prefix=`realpath ./install` --enable-sanitizer --cc=clang --cxx=clang++
```

## crash command
MP4Box -frag 0 -out /dev/null poc_file

## Pocs
[poc.zip](https://github.com/gpac/gpac/files/7950853/poc.zip)

## Crash output
poc_41.mp4

```
==19187==ERROR: AddressSanitizer: heap-use-after-free on address 0x603000001b17 at pc 0x0000010140cf bp 0x7ffd6975cff0 sp 0x7ffd6975cfe8
READ of size 1 at 0x603000001b17 thread T0
    #0 0x10140ce in mp4_mux_cenc_update /programs/mp4box/builds/build3/src/filters/mux_isom.c:3762:21
    #1 0x1017fdb in mp4_mux_process_sample /programs/mp4box/builds/build3/src/filters/mux_isom.c:4108:8
    #2 0x1009758 in mp4_mux_process_fragmented /programs/mp4box/builds/build3/src/filters/mux_isom.c:5599:8
    #3 0x10029a1 in mp4_mux_process /programs/mp4box/builds/build3/src/filters/mux_isom.c:6029:14
    #4 0xd8d4e9 in gf_filter_process_task /programs/mp4box/builds/build3/src/filter_core/filter.c:2515:7
    #5 0xd647ef in gf_fs_thread_proc /programs/mp4box/builds/build3/src/filter_core/filter_session.c:1756:3
    #6 0xd63523 in gf_fs_run /programs/mp4box/builds/build3/src/filter_core/filter_session.c:2000:2
    #7 0xaa99ff in gf_media_fragment_file /programs/mp4box/builds/build3/src/media_tools/isom_tools.c:3816:6
    #8 0x4ebaff in mp4boxMain /programs/mp4box/builds/build3/applications/mp4box/main.c:6455:7
    #9 0x7f9d091e20b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
    #10 0x41ea6d in _start (/programs/mp4box/builds/build3/bin/gcc/MP4Box+0x41ea6d)

0x603000001b17 is located 7 bytes inside of 23-byte region [0x603000001b10,0x603000001b27)
freed by thread T0 here:
    #0 0x499a62 in free (/programs/mp4box/builds/build3/bin/gcc/MP4Box+0x499a62)
    #1 0xa5e0b8 in gf_odf_avc_cfg_del /programs/mp4box/builds/build3/src/odf/descriptors.c:482:17
    #2 0x892f2e in avcc_box_del /programs/mp4box/builds/build3/src/isomedia/avc_ext.c:2728:19
    #3 0x8d76d4 in gf_isom_box_del /programs/mp4box/builds/build3/src/isomedia/box_funcs.c:1806:3
    #4 0x998f8b in gf_isom_update_sample_description_from_template /programs/mp4box/builds/build3/src/isomedia/isom_write.c:7789:4
    #5 0x1029564 in mp4_mux_setup_pid /programs/mp4box/builds/build3/src/filters/mux_isom.c:3102:4
    #6 0xd05416 in gf_filter_pid_configure /programs/mp4box/builds/build3/src/filter_core/filter_pid.c:752:6
    #7 0xd0b67f in gf_filter_pid_get_packet /programs/mp4box/builds/build3/src/filter_core/filter_pid.c:5612:8
    #8 0x1001b28 in mp4_mux_config_timing /programs/mp4box/builds/build3/src/filters/mux_isom.c:5805:9
    #9 0x1001b28 in mp4_mux_process /programs/mp4box/builds/build3/src/filters/mux_isom.c:6019:3
    #10 0xd8d4e9 in gf_filter_process_task /programs/mp4box/builds/build3/src/filter_core/filter.c:2515:7
    #11 0xd647ef in gf_fs_thread_proc /programs/mp4box/builds/build3/src/filter_core/filter_session.c:1756:3
    #12 0xd63523 in gf_fs_run /programs/mp4box/builds/build3/src/filter_core/filter_session.c:2000:2
    #13 0xaa99ff in gf_media_fragment_file /programs/mp4box/builds/build3/src/media_tools/isom_tools.c:3816:6
    #14 0x4ebaff in mp4boxMain /programs/mp4box/builds/build3/applications/mp4box/main.c:6455:7
    #15 0x7f9d091e20b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)

previously allocated by thread T0 here:
    #0 0x499ccd in malloc (/programs/mp4box/builds/build3/bin/gcc/MP4Box+0x499ccd)
    #1 0x8934fa in avcc_box_read /programs/mp4box/builds/build3/src/isomedia/avc_ext.c:2773:22
    #2 0x8d6e8d in gf_isom_box_parse_ex /programs/mp4box/builds/build3/src/isomedia/box_funcs.c:264:14
    #3 0x8d923d in gf_isom_box_array_read_ex /programs/mp4box/builds/build3/src/isomedia/box_funcs.c:1719:7
    #4 0x1584e5a in video_sample_entry_box_read /programs/mp4box/builds/build3/src/isomedia/box_code_base.c:4304:6
    #5 0x8d6e8d in gf_isom_box_parse_ex /programs/mp4box/builds/build3/src/isomedia/box_funcs.c:264:14
    #6 0x998ce2 in gf_isom_update_sample_description_from_template /programs/mp4box/builds/build3/src/isomedia/isom_write.c:7756:6
    #7 0x1029564 in mp4_mux_setup_pid /programs/mp4box/builds/build3/src/filters/mux_isom.c:3102:4
    #8 0xd05416 in gf_filter_pid_configure /programs/mp4box/builds/build3/src/filter_core/filter_pid.c:752:6
    #9 0xd0b67f in gf_filter_pid_get_packet /programs/mp4box/builds/build3/src/filter_core/filter_pid.c:5612:8
    #10 0x1001b28 in mp4_mux_config_timing /programs/mp4box/builds/build3/src/filters/mux_isom.c:5805:9
    #11 0x1001b28 in mp4_mux_process /programs/mp4box/builds/build3/src/filters/mux_isom.c:6019:3
    #12 0xd8d4e9 in gf_filter_process_task /programs/mp4box/builds/build3/src/filter_core/filter.c:2515:7
    #13 0xd647ef in gf_fs_thread_proc /programs/mp4box/builds/build3/src/filter_core/filter_session.c:1756:3
    #14 0xd63523 in gf_fs_run /programs/mp4box/builds/build3/src/filter_core/filter_session.c:2000:2
    #15 0xaa99ff in gf_media_fragment_file /programs/mp4box/builds/build3/src/media_tools/isom_tools.c:3816:6
    #16 0x4ebaff in mp4boxMain /programs/mp4box/builds/build3/applications/mp4box/main.c:6455:7
    #17 0x7f9d091e20b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)

SUMMARY: AddressSanitizer: heap-use-after-free /programs/mp4box/builds/build3/src/filters/mux_isom.c:3762:21 in mp4_mux_cenc_update
Shadow bytes around the buggy address:
  0x0c067fff8310: fd fa fa fa fd fd fd fa fa fa 00 00 00 00 fa fa
  0x0c067fff8320: 00 00 00 06 fa fa 00 00 00 00 fa fa 00 00 04 fa
  0x0c067fff8330: fa fa 00 00 00 00 fa fa 00 00 00 06 fa fa 00 00
  0x0c067fff8340: 00 fa fa fa 00 00 00 00 fa fa 00 00 00 fa fa fa
  0x0c067fff8350: 00 00 00 00 fa fa 00 00 00 fa fa fa fd fd fd fa
=>0x0c067fff8360: fa fa[fd]fd fd fa fa fa fd fd fd fa fa fa fd fd
  0x0c067fff8370: fd fa fa fa fd fd fd fa fa fa fd fd fd fa fa fa
  0x0c067fff8380: 00 00 00 fa fa fa fd fd fd fa fa fa 00 00 00 fa
  0x0c067fff8390: fa fa 00 00 00 00 fa fa 00 00 00 06 fa fa fd fd
  0x0c067fff83a0: fd fa fa fa fd fd fd fd fa fa 00 00 00 00 fa fa
  0x0c067fff83b0: 00 00 00 fa fa fa fd fd fd fa fa fa fd fd fd fd
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
==19187==ABORTING
```
--- end body ---
