## Description
There is a segment fault 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-rev1727-g8be34973d-master
```

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

## crash command
```
MP4Box -3gp -out /dev/null poc_file
```

## Pocs

[poc.zip](https://github.com/gpac/gpac/files/8020720/poc.zip)


## Crash output
```
==15809==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x0000012e0717 bp 0x7ffc1bf93500 sp 0x7ffc1bf934c0 T0)
==15809==The signal is caused by a READ memory access.
==15809==Hint: address points to the zero page.
    #0 0x12e0717 in stsz_box_write/programs/mp4box/builds/build10/src/isomedia/box_code_base.c
    #1 0x7b1a04 in gf_isom_box_write_listing/programs/mp4box/builds/build10/src/isomedia/box_funcs.c:1834:9
    #2 0x7b1a04 in gf_isom_box_write/programs/mp4box/builds/build10/src/isomedia/box_funcs.c:1883:6
    #3 0x803817 in WriteInterleaved/programs/mp4box/builds/build10/src/isomedia/isom_store.c:1879:9
    #4 0x8008a2 in WriteToFile/programs/mp4box/builds/build10/src/isomedia/isom_store.c
    #5 0x7d33b7 in gf_isom_write/programs/mp4box/builds/build10/src/isomedia/isom_read.c:600:8
    #6 0x7d3983 in gf_isom_close/programs/mp4box/builds/build10/src/isomedia/isom_read.c:624:6
    #7 0x4e765f in mp4boxMain/programs/mp4box/builds/build10/applications/mp4box/main.c:6547:7
    #8 0x7fe25fdd30b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
    #9 0x41ea6d in _start (/zhengjie/cmdline-fuzz/programs/mp4box/builds/build10/bin/gcc/MP4Box+0x41ea6d)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV/programs/mp4box/builds/build10/src/isomedia/box_code_base.c in stsz_box_write
==15809==ABORTING
```
There is a segment fault detected by AddressSanitizer
This is a GitHub Issue
repo:gpac
owner:gpac
Title : There is a segment fault detected by AddressSanitizer
Issue date:

--- start body ---
## Description
There is a segment fault 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-rev1727-g8be34973d-master
```

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

## crash command
```
MP4Box -3gp -out /dev/null poc_file
```

## Pocs

[poc.zip](https://github.com/gpac/gpac/files/8020720/poc.zip)


## Crash output
```
==15809==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x0000012e0717 bp 0x7ffc1bf93500 sp 0x7ffc1bf934c0 T0)
==15809==The signal is caused by a READ memory access.
==15809==Hint: address points to the zero page.
    #0 0x12e0717 in stsz_box_write/programs/mp4box/builds/build10/src/isomedia/box_code_base.c
    #1 0x7b1a04 in gf_isom_box_write_listing/programs/mp4box/builds/build10/src/isomedia/box_funcs.c:1834:9
    #2 0x7b1a04 in gf_isom_box_write/programs/mp4box/builds/build10/src/isomedia/box_funcs.c:1883:6
    #3 0x803817 in WriteInterleaved/programs/mp4box/builds/build10/src/isomedia/isom_store.c:1879:9
    #4 0x8008a2 in WriteToFile/programs/mp4box/builds/build10/src/isomedia/isom_store.c
    #5 0x7d33b7 in gf_isom_write/programs/mp4box/builds/build10/src/isomedia/isom_read.c:600:8
    #6 0x7d3983 in gf_isom_close/programs/mp4box/builds/build10/src/isomedia/isom_read.c:624:6
    #7 0x4e765f in mp4boxMain/programs/mp4box/builds/build10/applications/mp4box/main.c:6547:7
    #8 0x7fe25fdd30b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
    #9 0x41ea6d in _start (/zhengjie/cmdline-fuzz/programs/mp4box/builds/build10/bin/gcc/MP4Box+0x41ea6d)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV/programs/mp4box/builds/build10/src/isomedia/box_code_base.c in stsz_box_write
==15809==ABORTING
```
--- end body ---

A segmentation fault in the MP4Box application of GPAC version 1.1.0-DEV can be exploited by providing a specially crafted input file, leading to a Denial of Service (DoS). The crash occurs due to a null pointer dereference in the stsz_box_write function, as indicated by the AddressSanitizer output.