Thanks for reporting your issue. Please make sure these boxes are checked before submitting your issue - thank you!

- [Yes ] I looked for a similar issue and couldn't find any.
- [ Yes] I tried with the latest version of GPAC. Installers available at http://gpac.io/downloads/gpac-nightly-builds/
- [ Yes] I give enough information for contributors to reproduce my issue (meaningful title, github labels, platform and compiler, command-line ...). I can share files anonymously with this dropbox: https://www.mediafire.com/filedrop/filedrop_hosted.php?drop=eec9e058a9486fe4e99c33021481d9e1826ca9dbc242a6cfaab0fe95da5e5d95

Detailed guidelines: http://gpac.io/2013/07/16/how-to-file-a-bug-properly/

**Version:**
```
./MP4Box -version
MP4Box - GPAC version 1.1.0-DEV-rev1574-g8b22f0912-master
(c) 2000-2021 Telecom Paris distributed under LGPL v2.1+ - http://gpac.io

Please cite our work in your research:
 GPAC Filters: https://doi.org/10.1145/3339825.3394929
 GPAC: https://doi.org/10.1145/1291233.1291452

GPAC Configuration: 
Features: GPAC_CONFIG_LINUX GPAC_64_BITS GPAC_HAS_IPV6 GPAC_HAS_SSL GPAC_HAS_SOCK_UN GPAC_MINIMAL_ODF GPAC_HAS_QJS GPAC_HAS_JPEG GPAC_HAS_PNG GPAC_HAS_LINUX_DVB
```

**command:**
```
./bin/gcc/MP4Box -hint POC12
```

[POC12.zip](https://github.com/gpac/gpac/files/7772999/POC12.zip)

**Result**
```
Segmentation fault
```
**bt**

```
Program received signal SIGSEGV, Segmentation fault.
[----------------------------------registers-----------------------------------]
RAX: 0x0 
RBX: 0x0 
RCX: 0x0 
RDX: 0x7fffffff8440 --> 0x0 
RSI: 0x7fffffff8440 --> 0x0 
RDI: 0x41 ('A')
RBP: 0x41 ('A')
RSP: 0x7fffffff8150 --> 0xffffffffffffffff 
RIP: 0x7ffff7959856 (<gf_odf_desc_copy+38>:	cmp    BYTE PTR [rdi],0x3)
R8 : 0x5555555db390 --> 0x5555555e0550 --> 0x5555555dfbd0 --> 0x7472616b ('kart')
R9 : 0x0 
R10: 0x7ffff76d8ff8 ("gf_odf_desc_copy")
R11: 0x7ffff7959830 (<gf_odf_desc_copy>:	endbr64)
R12: 0x5555555e01b0 --> 0x6d703461 ('a4pm')
R13: 0x7fffffff8440 --> 0x0 
R14: 0x5555555e29d0 --> 0x73747364 ('dsts')
R15: 0x1
EFLAGS: 0x10246 (carry PARITY adjust ZERO sign trap INTERRUPT direction overflow)
[-------------------------------------code-------------------------------------]
   0x7ffff7959846 <gf_odf_desc_copy+22>:	mov    rax,QWORD PTR fs:0x28
   0x7ffff795984f <gf_odf_desc_copy+31>:	mov    QWORD PTR [rsp+0x18],rax
   0x7ffff7959854 <gf_odf_desc_copy+36>:	xor    eax,eax
=> 0x7ffff7959856 <gf_odf_desc_copy+38>:	cmp    BYTE PTR [rdi],0x3
   0x7ffff7959859 <gf_odf_desc_copy+41>:	je     0x7ffff79598a0 <gf_odf_desc_copy+112>
   0x7ffff795985b <gf_odf_desc_copy+43>:	lea    rdx,[rsp+0xc]
   0x7ffff7959860 <gf_odf_desc_copy+48>:	lea    rsi,[rsp+0x10]
   0x7ffff7959865 <gf_odf_desc_copy+53>:	mov    rdi,rbp
[------------------------------------stack-------------------------------------]
0000| 0x7fffffff8150 --> 0xffffffffffffffff 
0008| 0x7fffffff8158 --> 0x6 
0016| 0x7fffffff8160 --> 0x7fffffff8180 --> 0x5555555e01b0 --> 0x6d703461 ('a4pm')
0024| 0x7fffffff8168 --> 0x8b3c03504fc5800 
0032| 0x7fffffff8170 --> 0x0 
0040| 0x7fffffff8178 --> 0x7fffffff8440 --> 0x0 
0048| 0x7fffffff8180 --> 0x5555555e01b0 --> 0x6d703461 ('a4pm')
0056| 0x7fffffff8188 --> 0x41 ('A')
[------------------------------------------------------------------------------]
Legend: code, data, rodata, value
Stopped reason: SIGSEGV
0x00007ffff7959856 in gf_odf_desc_copy () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
gdb-peda$ bt
#0  0x00007ffff7959856 in gf_odf_desc_copy () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#1  0x00007ffff7927468 in Media_GetESD () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#2  0x00007ffff7906e27 in gf_isom_get_decoder_config () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#3  0x00007ffff790ead6 in gf_isom_guess_specification () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#4  0x0000555555579339 in HintFile ()
#5  0x000055555557d257 in mp4boxMain ()
#6  0x00007ffff74dc0b3 in __libc_start_main (main=0x55555556d420 <main>, argc=0x3, argv=0x7fffffffe388, init=<optimized out>, fini=<optimized out>, 
    rtld_fini=<optimized out>, stack_end=0x7fffffffe378) at ../csu/libc-start.c:308
#7  0x000055555556d45e in _start ()
gdb-peda$ 



```
Untrusted pointer dereference in gf_odf_desc_copy ()
This is a GitHub Issue
repo:gpac
owner:gpac
Title : Untrusted pointer dereference in gf_odf_desc_copy ()
Issue date:

--- start body ---
Thanks for reporting your issue. Please make sure these boxes are checked before submitting your issue - thank you!

- [Yes ] I looked for a similar issue and couldn't find any.
- [ Yes] I tried with the latest version of GPAC. Installers available at http://gpac.io/downloads/gpac-nightly-builds/
- [ Yes] I give enough information for contributors to reproduce my issue (meaningful title, github labels, platform and compiler, command-line ...). I can share files anonymously with this dropbox: https://www.mediafire.com/filedrop/filedrop_hosted.php?drop=eec9e058a9486fe4e99c33021481d9e1826ca9dbc242a6cfaab0fe95da5e5d95

Detailed guidelines: http://gpac.io/2013/07/16/how-to-file-a-bug-properly/

**Version:**
```
./MP4Box -version
MP4Box - GPAC version 1.1.0-DEV-rev1574-g8b22f0912-master
(c) 2000-2021 Telecom Paris distributed under LGPL v2.1+ - http://gpac.io

Please cite our work in your research:
 GPAC Filters: https://doi.org/10.1145/3339825.3394929
 GPAC: https://doi.org/10.1145/1291233.1291452

GPAC Configuration: 
Features: GPAC_CONFIG_LINUX GPAC_64_BITS GPAC_HAS_IPV6 GPAC_HAS_SSL GPAC_HAS_SOCK_UN GPAC_MINIMAL_ODF GPAC_HAS_QJS GPAC_HAS_JPEG GPAC_HAS_PNG GPAC_HAS_LINUX_DVB
```

**command:**
```
./bin/gcc/MP4Box -hint POC12
```

[POC12.zip](https://github.com/gpac/gpac/files/7772999/POC12.zip)

**Result**
```
Segmentation fault
```
**bt**

```
Program received signal SIGSEGV, Segmentation fault.
[----------------------------------registers-----------------------------------]
RAX: 0x0 
RBX: 0x0 
RCX: 0x0 
RDX: 0x7fffffff8440 --> 0x0 
RSI: 0x7fffffff8440 --> 0x0 
RDI: 0x41 ('A')
RBP: 0x41 ('A')
RSP: 0x7fffffff8150 --> 0xffffffffffffffff 
RIP: 0x7ffff7959856 (<gf_odf_desc_copy+38>:	cmp    BYTE PTR [rdi],0x3)
R8 : 0x5555555db390 --> 0x5555555e0550 --> 0x5555555dfbd0 --> 0x7472616b ('kart')
R9 : 0x0 
R10: 0x7ffff76d8ff8 ("gf_odf_desc_copy")
R11: 0x7ffff7959830 (<gf_odf_desc_copy>:	endbr64)
R12: 0x5555555e01b0 --> 0x6d703461 ('a4pm')
R13: 0x7fffffff8440 --> 0x0 
R14: 0x5555555e29d0 --> 0x73747364 ('dsts')
R15: 0x1
EFLAGS: 0x10246 (carry PARITY adjust ZERO sign trap INTERRUPT direction overflow)
[-------------------------------------code-------------------------------------]
   0x7ffff7959846 <gf_odf_desc_copy+22>:	mov    rax,QWORD PTR fs:0x28
   0x7ffff795984f <gf_odf_desc_copy+31>:	mov    QWORD PTR [rsp+0x18],rax
   0x7ffff7959854 <gf_odf_desc_copy+36>:	xor    eax,eax
=> 0x7ffff7959856 <gf_odf_desc_copy+38>:	cmp    BYTE PTR [rdi],0x3
   0x7ffff7959859 <gf_odf_desc_copy+41>:	je     0x7ffff79598a0 <gf_odf_desc_copy+112>
   0x7ffff795985b <gf_odf_desc_copy+43>:	lea    rdx,[rsp+0xc]
   0x7ffff7959860 <gf_odf_desc_copy+48>:	lea    rsi,[rsp+0x10]
   0x7ffff7959865 <gf_odf_desc_copy+53>:	mov    rdi,rbp
[------------------------------------stack-------------------------------------]
0000| 0x7fffffff8150 --> 0xffffffffffffffff 
0008| 0x7fffffff8158 --> 0x6 
0016| 0x7fffffff8160 --> 0x7fffffff8180 --> 0x5555555e01b0 --> 0x6d703461 ('a4pm')
0024| 0x7fffffff8168 --> 0x8b3c03504fc5800 
0032| 0x7fffffff8170 --> 0x0 
0040| 0x7fffffff8178 --> 0x7fffffff8440 --> 0x0 
0048| 0x7fffffff8180 --> 0x5555555e01b0 --> 0x6d703461 ('a4pm')
0056| 0x7fffffff8188 --> 0x41 ('A')
[------------------------------------------------------------------------------]
Legend: code, data, rodata, value
Stopped reason: SIGSEGV
0x00007ffff7959856 in gf_odf_desc_copy () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
gdb-peda$ bt
#0  0x00007ffff7959856 in gf_odf_desc_copy () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#1  0x00007ffff7927468 in Media_GetESD () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#2  0x00007ffff7906e27 in gf_isom_get_decoder_config () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#3  0x00007ffff790ead6 in gf_isom_guess_specification () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#4  0x0000555555579339 in HintFile ()
#5  0x000055555557d257 in mp4boxMain ()
#6  0x00007ffff74dc0b3 in __libc_start_main (main=0x55555556d420 <main>, argc=0x3, argv=0x7fffffffe388, init=<optimized out>, fini=<optimized out>, 
    rtld_fini=<optimized out>, stack_end=0x7fffffffe378) at ../csu/libc-start.c:308
#7  0x000055555556d45e in _start ()
gdb-peda$ 



```
--- end body ---
