A Pointer Dereference Vulnerabilty exists in GPAC 1.0.1 via the finplace_shift_moov_meta_offsets function, which causes a Denial of Servie (context-dependent).
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 POC6
```

[POC6.zip](https://github.com/gpac/gpac/files/7763917/POC6.zip)


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

```
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7910358 in inplace_shift_moov_meta_offsets () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
LEGEND: STACK | HEAP | CODE | DATA | RWX | RODATA
───────────────────────────────────────────────────────────────────────[ REGISTERS ]────────────────────────────────────────────────────────────────────────
 RAX  0x5569555e0d34
 RBX  0x5555555e0000 ◂— 0x7374626c /* 'lbts' */
 RCX  0x0
 RDX  0x14
 RDI  0x5555555db330 —▸ 0x5555555e0640 ◂— 0x5569555dfab4
 RSI  0x1
 R8   0x0
 R9   0x7fffffff7f00 —▸ 0x7ffff76a15c0 (_IO_2_1_stderr_) ◂— 0xfbad2887
 R10  0x7ffff76d927a ◂— 'gf_isom_box_size'
 R11  0x7ffff78fa0d0 (gf_isom_box_size) ◂— endbr64 
 R12  0x5555555da950 ◂— 0x0
 R13  0x14
 R14  0x2
 R15  0x7fffffff7fd0 ◂— 0x0
 RBP  0x1
 RSP  0x7fffffff7fd0 ◂— 0x0
 RIP  0x7ffff7910358 (inplace_shift_moov_meta_offsets+152) ◂— mov    rdi, qword ptr [rax + 0x50]
[ DISASM ]
 ► 0x7ffff7910358 <inplace_shift_moov_meta_offsets+152>    mov    rdi, qword ptr [rax + 0x50]
   0x7ffff791035c <inplace_shift_moov_meta_offsets+156>    mov    rbx, rax
   0x7ffff791035f <inplace_shift_moov_meta_offsets+159>    test   rdi, rdi
   0x7ffff7910362 <inplace_shift_moov_meta_offsets+162>    je     inplace_shift_moov_meta_offsets+176                <inplace_shift_moov_meta_offsets+176>
    ↓
   0x7ffff7910370 <inplace_shift_moov_meta_offsets+176>    mov    rsi, qword ptr [rbx + 0x38]
   0x7ffff7910374 <inplace_shift_moov_meta_offsets+180>    movzx  r8d, byte ptr [r12 + 0x37]
   0x7ffff791037a <inplace_shift_moov_meta_offsets+186>    mov    rax, qword ptr [rsi + 0x40]
   0x7ffff791037e <inplace_shift_moov_meta_offsets+190>    mov    rbx, qword ptr [rax + 0x30]
   0x7ffff7910382 <inplace_shift_moov_meta_offsets+194>    mov    rdi, qword ptr [rbx + 0x58]
   0x7ffff7910386 <inplace_shift_moov_meta_offsets+198>    mov    rdx, qword ptr [rbx + 0x60]
   0x7ffff791038a <inplace_shift_moov_meta_offsets+202>    test   rdi, rdi
[ STACK ]
00:0000│ r15 rsp 0x7fffffff7fd0 ◂— 0x0
01:0008│         0x7fffffff7fd8 ◂— 0x3fa7125e0eb52b00
02:0010│         0x7fffffff7fe0 ◂— 0x0
03:0018│         0x7fffffff7fe8 —▸ 0x5555555da950 ◂— 0x0
04:0020│         0x7fffffff7ff0 —▸ 0x5555555df7a0 —▸ 0x5555555e5720 ◂— 0xfbad2480
05:0028│         0x7fffffff7ff8 ◂— 0x0
06:0030│         0x7fffffff8000 —▸ 0x7fffffff84d8 ◂— 0x14
07:0038│         0x7fffffff8008 —▸ 0x7fffffff84e0 ◂— 0x0
[ BACKTRACE ]
 ► f 0   0x7ffff7910358 inplace_shift_moov_meta_offsets+152
   f 1   0x7ffff7910e3c inplace_shift_mdat+732
   f 2   0x7ffff7915009 WriteToFile+2713
   f 3   0x7ffff7906432 gf_isom_write+370
   f 4   0x7ffff79064b8 gf_isom_close+24
   f 5   0x55555557bd12 mp4boxMain+7410
   f 6   0x7ffff74dc0b3 __libc_start_main+243
─────────────────────────────────────────────────────
```
Untrusted pointer dereference in inplace_shift_moov_meta_offsets ()
This is a GitHub Issue
repo:gpac
owner:gpac
Title : Untrusted pointer dereference in inplace_shift_moov_meta_offsets ()
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 POC6
```

[POC6.zip](https://github.com/gpac/gpac/files/7763917/POC6.zip)


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

```
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7910358 in inplace_shift_moov_meta_offsets () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
LEGEND: STACK | HEAP | CODE | DATA | RWX | RODATA
───────────────────────────────────────────────────────────────────────[ REGISTERS ]────────────────────────────────────────────────────────────────────────
 RAX  0x5569555e0d34
 RBX  0x5555555e0000 ◂— 0x7374626c /* 'lbts' */
 RCX  0x0
 RDX  0x14
 RDI  0x5555555db330 —▸ 0x5555555e0640 ◂— 0x5569555dfab4
 RSI  0x1
 R8   0x0
 R9   0x7fffffff7f00 —▸ 0x7ffff76a15c0 (_IO_2_1_stderr_) ◂— 0xfbad2887
 R10  0x7ffff76d927a ◂— 'gf_isom_box_size'
 R11  0x7ffff78fa0d0 (gf_isom_box_size) ◂— endbr64 
 R12  0x5555555da950 ◂— 0x0
 R13  0x14
 R14  0x2
 R15  0x7fffffff7fd0 ◂— 0x0
 RBP  0x1
 RSP  0x7fffffff7fd0 ◂— 0x0
 RIP  0x7ffff7910358 (inplace_shift_moov_meta_offsets+152) ◂— mov    rdi, qword ptr [rax + 0x50]
[ DISASM ]
 ► 0x7ffff7910358 <inplace_shift_moov_meta_offsets+152>    mov    rdi, qword ptr [rax + 0x50]
   0x7ffff791035c <inplace_shift_moov_meta_offsets+156>    mov    rbx, rax
   0x7ffff791035f <inplace_shift_moov_meta_offsets+159>    test   rdi, rdi
   0x7ffff7910362 <inplace_shift_moov_meta_offsets+162>    je     inplace_shift_moov_meta_offsets+176                <inplace_shift_moov_meta_offsets+176>
    ↓
   0x7ffff7910370 <inplace_shift_moov_meta_offsets+176>    mov    rsi, qword ptr [rbx + 0x38]
   0x7ffff7910374 <inplace_shift_moov_meta_offsets+180>    movzx  r8d, byte ptr [r12 + 0x37]
   0x7ffff791037a <inplace_shift_moov_meta_offsets+186>    mov    rax, qword ptr [rsi + 0x40]
   0x7ffff791037e <inplace_shift_moov_meta_offsets+190>    mov    rbx, qword ptr [rax + 0x30]
   0x7ffff7910382 <inplace_shift_moov_meta_offsets+194>    mov    rdi, qword ptr [rbx + 0x58]
   0x7ffff7910386 <inplace_shift_moov_meta_offsets+198>    mov    rdx, qword ptr [rbx + 0x60]
   0x7ffff791038a <inplace_shift_moov_meta_offsets+202>    test   rdi, rdi
[ STACK ]
00:0000│ r15 rsp 0x7fffffff7fd0 ◂— 0x0
01:0008│         0x7fffffff7fd8 ◂— 0x3fa7125e0eb52b00
02:0010│         0x7fffffff7fe0 ◂— 0x0
03:0018│         0x7fffffff7fe8 —▸ 0x5555555da950 ◂— 0x0
04:0020│         0x7fffffff7ff0 —▸ 0x5555555df7a0 —▸ 0x5555555e5720 ◂— 0xfbad2480
05:0028│         0x7fffffff7ff8 ◂— 0x0
06:0030│         0x7fffffff8000 —▸ 0x7fffffff84d8 ◂— 0x14
07:0038│         0x7fffffff8008 —▸ 0x7fffffff84e0 ◂— 0x0
[ BACKTRACE ]
 ► f 0   0x7ffff7910358 inplace_shift_moov_meta_offsets+152
   f 1   0x7ffff7910e3c inplace_shift_mdat+732
   f 2   0x7ffff7915009 WriteToFile+2713
   f 3   0x7ffff7906432 gf_isom_write+370
   f 4   0x7ffff79064b8 gf_isom_close+24
   f 5   0x55555557bd12 mp4boxMain+7410
   f 6   0x7ffff74dc0b3 __libc_start_main+243
─────────────────────────────────────────────────────
```
--- end body ---
