nrUE NAS: check NAS COUNT UL

It should not be > 0xffffff.

Normally the core network would prevent this case from happening.
Plus to reach this value means to send a lot of NAS messages, which
is very doubtful in practice.

Anyway, it's better to deal with the case.

We exit if that happens. To be refined if needed (very doubtful).

openair3/NAS/NR_UE/nr_nas_msg_sim.c

@@ -668,6 +668,7 @@ static void generateSecurityModeComplete(nr_ue_nas_t *nas, as_nas_info_t *initia
   /* ciphering */
   uint8_t buf[initialNasMsg->length - 7];
   stream_cipher.context    = nas->security_container->ciphering_context;
+  AssertFatal(nas->security.nas_count_ul <= 0xffffff, "fatal: NAS COUNT UL too big (todo: fix that)\n");
   stream_cipher.count      = nas->security.nas_count_ul;
   stream_cipher.bearer     = 1;
   stream_cipher.direction  = 0;
@@ -814,6 +815,7 @@ static void generateRegistrationComplete(nr_ue_nas_t *nas, as_nas_info_t *initia
   /* ciphering */
   uint8_t buf[initialNasMsg->length - 7];
   stream_cipher.context    = nas->security_container->ciphering_context;
+  AssertFatal(nas->security.nas_count_ul <= 0xffffff, "fatal: NAS COUNT UL too big (todo: fix that)\n");
   stream_cipher.count      = nas->security.nas_count_ul;
   stream_cipher.bearer     = 1;
   stream_cipher.direction  = 0;
@@ -888,6 +890,7 @@ static void generateDeregistrationRequest(nr_ue_nas_t *nas, as_nas_info_t *initi
   /* ciphering */
   uint8_t buf[initialNasMsg->length - 7];
   stream_cipher.context    = nas->security_container->ciphering_context;
+  AssertFatal(nas->security.nas_count_ul <= 0xffffff, "fatal: NAS COUNT UL too big (todo: fix that)\n");
   stream_cipher.count      = nas->security.nas_count_ul;
   stream_cipher.bearer     = 1;
   stream_cipher.direction  = 0;
@@ -993,6 +996,7 @@ static void generatePduSessionEstablishRequest(nr_ue_nas_t *nas, as_nas_info_t *
   /* ciphering */
   uint8_t buf[initialNasMsg->length - 7];
   stream_cipher.context    = nas->security_container->ciphering_context;
+  AssertFatal(nas->security.nas_count_ul <= 0xffffff, "fatal: NAS COUNT UL too big (todo: fix that)\n");
   stream_cipher.count      = nas->security.nas_count_ul;
   stream_cipher.bearer     = 1;
   stream_cipher.direction  = 0;