There is a Null Pointer Dereference in function filter_core/filter_pck.c:gf_filter_pck_new_alloc_internal in GPAC 1.0.1. The pid comes from function av1dmx_parse_flush_sample, the ctx.opid maybe NULL. The result is a crash in gf_filter_pck_new_alloc_internal.
There is a `Null Pointer Dereference` in function `filter_core/filter_pck.c:104:gf_filter_pck_new_alloc_internal`，
The `pid` comes from function `av1dmx_parse_flush_sample`, the `ctx.opid` maybe NULL.
Result a crash in `gf_filter_pck_new_alloc_internal`.


In command line:
gpac -info bug2
![bug2_cmd](https://user-images.githubusercontent.com/44844446/112789951-d3522b00-9090-11eb-998c-bd212ca0faeb.png)

In gdb:
![bug2](https://user-images.githubusercontent.com/44844446/112789958-d5b48500-9090-11eb-8069-571218de0f0a.png)
The crafted file is in attach zip:
[bug2.zip](https://github.com/gpac/gpac/files/6219469/bug2.zip)



A Null Pointer Dereference In gf_filter_pck_new_alloc_internal
This is a GitHub Issue
repo:gpac
owner:gpac
Title : A Null Pointer Dereference In gf_filter_pck_new_alloc_internal
Issue date:

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There is a `Null Pointer Dereference` in function `filter_core/filter_pck.c:104:gf_filter_pck_new_alloc_internal`，
The `pid` comes from function `av1dmx_parse_flush_sample`, the `ctx.opid` maybe NULL.
Result a crash in `gf_filter_pck_new_alloc_internal`.


In command line:
gpac -info bug2
![bug2_cmd](https://user-images.githubusercontent.com/44844446/112789951-d3522b00-9090-11eb-998c-bd212ca0faeb.png)

In gdb:
![bug2](https://user-images.githubusercontent.com/44844446/112789958-d5b48500-9090-11eb-8069-571218de0f0a.png)
The crafted file is in attach zip:
[bug2.zip](https://github.com/gpac/gpac/files/6219469/bug2.zip)



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