## 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 -frag 0 -out /dev/null poc_file
```

## Pocs

[poc.zip](https://github.com/gpac/gpac/files/8020724/poc.zip)


## Crash output
```
==18741==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000010 (pc 0x000000d0c39d bp 0x7ffe59676990 sp 0x7ffe59676820 T0)
==18741==The signal is caused by a WRITE memory access.
==18741==Hint: address points to the zero page.
    #0 0xd0c39d in isor_reader_get_sample/programs/mp4box/builds/build10/src/filters/isoffin_read_ch.c:367:22
    #1 0xd04498 in isoffin_process/programs/mp4box/builds/build10/src/filters/isoffin_read.c:1311:5
    #2 0xb7d866 in gf_filter_process_task/programs/mp4box/builds/build10/src/filter_core/filter.c:2555:7
    #3 0xb5e41b in gf_fs_thread_proc/programs/mp4box/builds/build10/src/filter_core/filter_session.c:1793:3
    #4 0xb5d2c4 in gf_fs_run/programs/mp4box/builds/build10/src/filter_core/filter_session.c:2037:2
    #5 0x911200 in gf_media_fragment_file/programs/mp4box/builds/build10/src/media_tools/isom_tools.c:3821:6
    #6 0x4e6fcc in mp4boxMain/programs/mp4box/builds/build10/applications/mp4box/main.c:6455:7
    #7 0x7f87ce7a50b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
    #8 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/filters/isoffin_read_ch.c:367:22 in isor_reader_get_sample
==18741==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 -frag 0 -out /dev/null poc_file
```

## Pocs

[poc.zip](https://github.com/gpac/gpac/files/8020724/poc.zip)


## Crash output
```
==18741==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000010 (pc 0x000000d0c39d bp 0x7ffe59676990 sp 0x7ffe59676820 T0)
==18741==The signal is caused by a WRITE memory access.
==18741==Hint: address points to the zero page.
    #0 0xd0c39d in isor_reader_get_sample/programs/mp4box/builds/build10/src/filters/isoffin_read_ch.c:367:22
    #1 0xd04498 in isoffin_process/programs/mp4box/builds/build10/src/filters/isoffin_read.c:1311:5
    #2 0xb7d866 in gf_filter_process_task/programs/mp4box/builds/build10/src/filter_core/filter.c:2555:7
    #3 0xb5e41b in gf_fs_thread_proc/programs/mp4box/builds/build10/src/filter_core/filter_session.c:1793:3
    #4 0xb5d2c4 in gf_fs_run/programs/mp4box/builds/build10/src/filter_core/filter_session.c:2037:2
    #5 0x911200 in gf_media_fragment_file/programs/mp4box/builds/build10/src/media_tools/isom_tools.c:3821:6
    #6 0x4e6fcc in mp4boxMain/programs/mp4box/builds/build10/applications/mp4box/main.c:6455:7
    #7 0x7f87ce7a50b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
    #8 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/filters/isoffin_read_ch.c:367:22 in isor_reader_get_sample
==18741==ABORTING
```
--- end body ---

A segmentation fault in the GPAC MP4Box application, specifically in the isor_reader_get_sample function, indicates a potential vulnerability that could be exploited to cause a Denial of Service (DoS) by providing a specially crafted input file. The crash occurs due to a write access to an invalid memory address, which could lead to application instability or crashes.