nimble/audio: Bound broadcast sink subgroup count

Reject sync requests whose subgroup count exceeds the broadcast
sink subgroup array before copying BIS sync values into it.

The previous code relied on a debug assertion in the scan
delegator path, but production builds can still receive an
oversized sync option.

Fixes #2188

Author: aineoae86-sys

nimble/host/audio/src/ble_audio_broadcast_sink.c

@@ -1579,13 +1579,23 @@ ble_audio_broadcast_sink_config(uint8_t source_id, uint16_t conn_handle,
                                 const struct ble_audio_scan_delegator_sync_opt *sync_opt)
 {
     struct ble_audio_broadcast_sink *sink;
+    bool sync_requested;
     int rc;
 
     BLE_AUDIO_DBG_ASSERT(sync_opt != NULL);
 
+    sync_requested =
+        sync_opt->pa_sync != BLE_AUDIO_SCAN_DELEGATOR_PA_SYNC_DO_NOT_SYNC;
+    if (sync_requested &&
+        sync_opt->num_subgroups >
+        MYNEWT_VAL(BLE_AUDIO_SCAN_DELEGATOR_SUBGROUP_MAX)) {
+        BLE_HS_LOG_ERROR("num_subgroups above the limit\n");
+        return BLE_HS_EINVAL;
+    }
+
     sink = broadcast_sink_get(source_id);
     if (sink == NULL) {
-        if (sync_opt->pa_sync != BLE_AUDIO_SCAN_DELEGATOR_PA_SYNC_DO_NOT_SYNC) {
+        if (sync_requested) {
             sink = broadcast_sink_new(source_id);
             if (sink == NULL) {
                 return BLE_HS_ENOMEM;
@@ -1596,7 +1606,7 @@ ble_audio_broadcast_sink_config(uint8_t source_id, uint16_t conn_handle,
         }
     }
 
-    if (sync_opt->pa_sync != BLE_AUDIO_SCAN_DELEGATOR_PA_SYNC_DO_NOT_SYNC) {
+    if (sync_requested) {
         /* TODO: Skip if the BIS Sync is same */
         if (sink->num_subgroups != 0) {
             rc = big_sync_term(sink);

nimble/host/audio/test/src/ble_audio_test.c

@@ -22,11 +22,13 @@
 
 TEST_SUITE_DECL(ble_audio_base_parse_test_suite);
 TEST_CASE_DECL(ble_audio_listener_register_test);
+TEST_CASE_DECL(ble_audio_broadcast_sink_config_test_subgroups_bound);
 
 TEST_SUITE(ble_audio_test)
 {
     ble_audio_base_parse_test_suite();
     ble_audio_listener_register_test();
+    ble_audio_broadcast_sink_config_test_subgroups_bound();
 }
 
 int

nimble/host/audio/test/src/testcases/ble_audio_broadcast_sink_test.c

@@ -0,0 +1,38 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include "testutil/testutil.h"
+
+#include "host/ble_hs.h"
+#include "audio/ble_audio_scan_delegator.h"
+#include "../../../src/ble_audio_broadcast_sink_priv.h"
+
+TEST_CASE_SELF(ble_audio_broadcast_sink_config_test_subgroups_bound)
+{
+    struct ble_audio_scan_delegator_sync_opt sync_opt = {0};
+    int rc;
+
+    sync_opt.pa_sync = BLE_AUDIO_SCAN_DELEGATOR_PA_SYNC_PAST_NOT_AVAILABLE;
+    sync_opt.num_subgroups = BLE_AUDIO_SCAN_DELEGATOR_SUBGROUP_MAX + 1;
+
+    rc = ble_audio_broadcast_sink_config(0, BLE_HS_CONN_HANDLE_NONE,
+                                         &sync_opt);
+
+    TEST_ASSERT(rc == BLE_HS_EINVAL);
+}

nimble/host/audio/test/syscfg.yml

@@ -29,3 +29,7 @@ syscfg.vals:
   BLE_HS_DEBUG: 1
 
   BLE_EXT_ADV: 1
+
+  BLE_ISO_BROADCAST_SINK: 1
+  BLE_AUDIO_BROADCAST_SINK: 1
+  BLE_AUDIO_BROADCAST_SINK_MAX: 1