A Pointer Dereference Vulnerabilty exists in GPAC 1.0.1via ShiftMetaOffset.isra, which causes a Denial of Service (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 POC9
```
[POC9.zip](https://github.com/gpac/gpac/files/7764491/POC9.zip)



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

```
Program received signal SIGSEGV, Segmentation fault.
[----------------------------------registers-----------------------------------]
RAX: 0x5555555e4cc0 --> 0x147472617f 
RBX: 0x5555555e4cc0 --> 0x147472617f 
RCX: 0x0 
RDX: 0x17 
RSI: 0x14 
RDI: 0x1400000054 
RBP: 0x3 
RSP: 0x7fffffff7f78 --> 0x7ffff7910370 (<inplace_shift_moov_meta_offsets+176>:	mov    rsi,QWORD PTR [rbx+0x38])
RIP: 0x7ffff790fe70 (<ShiftMetaOffset.isra.0>:	mov    rax,QWORD PTR [rdi])
R8 : 0x0 
R9 : 0x7fffffff7f00 --> 0x5555555e4c34 --> 0xe8 
R10: 0x7ffff76d927a ("gf_isom_box_size")
R11: 0x7ffff78fa0d0 (<gf_isom_box_size>:	endbr64)
R12: 0x5555555da950 --> 0xffffffec 
R13: 0x14 
R14: 0x7 
R15: 0x7fffffff7f80 --> 0x0
EFLAGS: 0x10202 (carry parity adjust zero sign trap INTERRUPT direction overflow)
[-------------------------------------code-------------------------------------]
   0x7ffff790fe60 <gf_isom_get_content_light_level_info+128>:	ret    
   0x7ffff790fe61:	nop    WORD PTR cs:[rax+rax*1+0x0]
   0x7ffff790fe6b:	nop    DWORD PTR [rax+rax*1+0x0]
=> 0x7ffff790fe70 <ShiftMetaOffset.isra.0>:	mov    rax,QWORD PTR [rdi]
   0x7ffff790fe73 <ShiftMetaOffset.isra.0+3>:	test   rax,rax
   0x7ffff790fe76 <ShiftMetaOffset.isra.0+6>:	je     0x7ffff790ff60 <ShiftMetaOffset.isra.0+240>
   0x7ffff790fe7c <ShiftMetaOffset.isra.0+12>:	push   r15
   0x7ffff790fe7e <ShiftMetaOffset.isra.0+14>:	push   r14
[------------------------------------stack-------------------------------------]
0000| 0x7fffffff7f78 --> 0x7ffff7910370 (<inplace_shift_moov_meta_offsets+176>:	mov    rsi,QWORD PTR [rbx+0x38])
0008| 0x7fffffff7f80 --> 0x0 
0016| 0x7fffffff7f88 --> 0x82af77da4fe8b600 
0024| 0x7fffffff7f90 --> 0x0 
0032| 0x7fffffff7f98 --> 0x5555555da950 --> 0xffffffec 
0040| 0x7fffffff7fa0 --> 0x5555555df7a0 --> 0x5555555f02f0 --> 0xfbad2480 
0048| 0x7fffffff7fa8 --> 0x0 
0056| 0x7fffffff7fb0 --> 0x7fffffff8488 --> 0x14 
[------------------------------------------------------------------------------]
Legend: code, data, rodata, value
Stopped reason: SIGSEGV
0x00007ffff790fe70 in ShiftMetaOffset.isra.0 () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
gdb-peda$ bt
#0  0x00007ffff790fe70 in ShiftMetaOffset.isra.0 () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#1  0x00007ffff7910370 in inplace_shift_moov_meta_offsets () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#2  0x00007ffff7910e3c in inplace_shift_mdat () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#3  0x00007ffff7915009 in WriteToFile () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#4  0x00007ffff7906432 in gf_isom_write () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#5  0x00007ffff79064b8 in gf_isom_close () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#6  0x000055555557bd12 in mp4boxMain ()
#7  0x00007ffff74dc0b3 in __libc_start_main (main=0x55555556d420 <main>, argc=0x3, argv=0x7fffffffe318, init=<optimized out>, fini=<optimized out>, 
    rtld_fini=<optimized out>, stack_end=0x7fffffffe308) at ../csu/libc-start.c:308
#8  0x000055555556d45e in _start ()
```
Untrusted pointer dereference in ShiftMetaOffset.isra.0 ()
This is a GitHub Issue
repo:gpac
owner:gpac
Title : Untrusted pointer dereference in ShiftMetaOffset.isra.0 ()
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 POC9
```
[POC9.zip](https://github.com/gpac/gpac/files/7764491/POC9.zip)



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

```
Program received signal SIGSEGV, Segmentation fault.
[----------------------------------registers-----------------------------------]
RAX: 0x5555555e4cc0 --> 0x147472617f 
RBX: 0x5555555e4cc0 --> 0x147472617f 
RCX: 0x0 
RDX: 0x17 
RSI: 0x14 
RDI: 0x1400000054 
RBP: 0x3 
RSP: 0x7fffffff7f78 --> 0x7ffff7910370 (<inplace_shift_moov_meta_offsets+176>:	mov    rsi,QWORD PTR [rbx+0x38])
RIP: 0x7ffff790fe70 (<ShiftMetaOffset.isra.0>:	mov    rax,QWORD PTR [rdi])
R8 : 0x0 
R9 : 0x7fffffff7f00 --> 0x5555555e4c34 --> 0xe8 
R10: 0x7ffff76d927a ("gf_isom_box_size")
R11: 0x7ffff78fa0d0 (<gf_isom_box_size>:	endbr64)
R12: 0x5555555da950 --> 0xffffffec 
R13: 0x14 
R14: 0x7 
R15: 0x7fffffff7f80 --> 0x0
EFLAGS: 0x10202 (carry parity adjust zero sign trap INTERRUPT direction overflow)
[-------------------------------------code-------------------------------------]
   0x7ffff790fe60 <gf_isom_get_content_light_level_info+128>:	ret    
   0x7ffff790fe61:	nop    WORD PTR cs:[rax+rax*1+0x0]
   0x7ffff790fe6b:	nop    DWORD PTR [rax+rax*1+0x0]
=> 0x7ffff790fe70 <ShiftMetaOffset.isra.0>:	mov    rax,QWORD PTR [rdi]
   0x7ffff790fe73 <ShiftMetaOffset.isra.0+3>:	test   rax,rax
   0x7ffff790fe76 <ShiftMetaOffset.isra.0+6>:	je     0x7ffff790ff60 <ShiftMetaOffset.isra.0+240>
   0x7ffff790fe7c <ShiftMetaOffset.isra.0+12>:	push   r15
   0x7ffff790fe7e <ShiftMetaOffset.isra.0+14>:	push   r14
[------------------------------------stack-------------------------------------]
0000| 0x7fffffff7f78 --> 0x7ffff7910370 (<inplace_shift_moov_meta_offsets+176>:	mov    rsi,QWORD PTR [rbx+0x38])
0008| 0x7fffffff7f80 --> 0x0 
0016| 0x7fffffff7f88 --> 0x82af77da4fe8b600 
0024| 0x7fffffff7f90 --> 0x0 
0032| 0x7fffffff7f98 --> 0x5555555da950 --> 0xffffffec 
0040| 0x7fffffff7fa0 --> 0x5555555df7a0 --> 0x5555555f02f0 --> 0xfbad2480 
0048| 0x7fffffff7fa8 --> 0x0 
0056| 0x7fffffff7fb0 --> 0x7fffffff8488 --> 0x14 
[------------------------------------------------------------------------------]
Legend: code, data, rodata, value
Stopped reason: SIGSEGV
0x00007ffff790fe70 in ShiftMetaOffset.isra.0 () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
gdb-peda$ bt
#0  0x00007ffff790fe70 in ShiftMetaOffset.isra.0 () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#1  0x00007ffff7910370 in inplace_shift_moov_meta_offsets () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#2  0x00007ffff7910e3c in inplace_shift_mdat () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#3  0x00007ffff7915009 in WriteToFile () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#4  0x00007ffff7906432 in gf_isom_write () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#5  0x00007ffff79064b8 in gf_isom_close () from /home/zxq/CVE_testing/source/gpac/bin/gcc/libgpac.so.10
#6  0x000055555557bd12 in mp4boxMain ()
#7  0x00007ffff74dc0b3 in __libc_start_main (main=0x55555556d420 <main>, argc=0x3, argv=0x7fffffffe318, init=<optimized out>, fini=<optimized out>, 
    rtld_fini=<optimized out>, stack_end=0x7fffffffe308) at ../csu/libc-start.c:308
#8  0x000055555556d45e in _start ()
```
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