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From:   Simon Mikuda <simon.mikuda@streamunlimited.com>
To:     linux-bluetooth@vger.kernel.org
Cc:     Simon Mikuda <simon.mikuda@streamunlimited.com>
Subject: [PATCH] advertising: Fix crash when advertisement is unregistered while MGMT ADD_ADVERTISEMENT call
Date:   Thu, 31 Oct 2019 07:52:57 +0100
Message-Id: <1572504777-12124-1-git-send-email-simon.mikuda@streamunlimited.com>
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Sender: linux-bluetooth-owner@vger.kernel.org
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bluetoothd[29698]: src/advertising.c:register_advertisement() RegisterAdvertisement
bluetoothd[29698]: src/advertising.c:client_create() Adding proxy for /org/bluez/example/advertisement0
bluetoothd[29698]: src/advertising.c:register_advertisement() Registered advertisement at path /org/bluez/example/advertisement0
bluetoothd[29698]: src/advertising.c:parse_service_uuids() Adding ServiceUUID: 180D
bluetoothd[29698]: src/advertising.c:parse_service_uuids() Adding ServiceUUID: 180F
bluetoothd[29698]: src/advertising.c:parse_manufacturer_data() Adding ManufacturerData for ffff
bluetoothd[29698]: src/advertising.c:parse_service_data() Adding ServiceData for 9999
bluetoothd[29698]: src/advertising.c:parse_data() Adding Data for type 0x26 len 3
bluetoothd[29698]: src/advertising.c:refresh_adv() Refreshing advertisement: /org/bluez/example/advertisement0
bluetoothd[29698]: src/advertising.c:unregister_advertisement() UnregisterAdvertisement
bluetoothd[29698]: src/advertising.c:add_adv_callback() Advertisement registered: �
Segmentation fault (core dumped)
---
 src/advertising.c | 53 +++++++++++++++++++++++++++++------------------------
 1 file changed, 29 insertions(+), 24 deletions(-)

diff --git a/src/advertising.c b/src/advertising.c
index 3ed1376..7d8cadf 100644
--- a/src/advertising.c
+++ b/src/advertising.c
@@ -63,6 +63,8 @@ struct btd_adv_manager {
 #define AD_TYPE_PERIPHERAL 1
 
 struct btd_adv_client {
+	int ref_count;
+
 	struct btd_adv_manager *manager;
 	char *owner;
 	char *path;
@@ -136,13 +138,6 @@ static void client_free(void *data)
 	free(client);
 }
 
-static gboolean client_free_idle_cb(void *data)
-{
-	client_free(data);
-
-	return FALSE;
-}
-
 static void client_release(void *data)
 {
 	struct btd_adv_client *client = data;
@@ -175,12 +170,19 @@ static void remove_advertising(struct btd_adv_manager *manager,
 			manager->mgmt_index, sizeof(cp), &cp, NULL, NULL, NULL);
 }
 
-static void client_remove(void *data)
+static struct btd_adv_client *client_ref(struct btd_adv_client *client)
+{
+	__sync_fetch_and_add(&client->ref_count, 1);
+
+	return client;
+}
+
+static void client_unref(struct btd_adv_client *client)
 {
-	struct btd_adv_client *client = data;
 	struct mgmt_cp_remove_advertising cp;
 
-	g_dbus_client_set_disconnect_watch(client->client, NULL, NULL);
+	if (__sync_sub_and_fetch(&client->ref_count, 1))
+		return;
 
 	cp.instance = client->instance;
 
@@ -188,10 +190,6 @@ static void client_remove(void *data)
 			client->manager->mgmt_index, sizeof(cp), &cp,
 			NULL, NULL, NULL);
 
-	queue_remove(client->manager->clients, client);
-
-	g_idle_add(client_free_idle_cb, client);
-
 	g_dbus_emit_property_changed(btd_get_dbus_connection(),
 				adapter_get_path(client->manager->adapter),
 				LE_ADVERTISING_MGR_IFACE, "SupportedInstances");
@@ -199,13 +197,18 @@ static void client_remove(void *data)
 	g_dbus_emit_property_changed(btd_get_dbus_connection(),
 				adapter_get_path(client->manager->adapter),
 				LE_ADVERTISING_MGR_IFACE, "ActiveInstances");
+
+	queue_remove(client->manager->clients, client);
+
+	client_free(client);
+
 }
 
 static void client_disconnect_cb(DBusConnection *conn, void *user_data)
 {
 	DBG("Client disconnected");
 
-	client_remove(user_data);
+	client_unref(user_data);
 }
 
 static bool parse_type(DBusMessageIter *iter, struct btd_adv_client *client)
@@ -564,7 +567,7 @@ static gboolean client_timeout(void *user_data)
 	client->to_id = 0;
 
 	client_release(client);
-	client_remove(client);
+	client_unref(client);
 
 	return FALSE;
 }
@@ -963,8 +966,6 @@ static void add_client_complete(struct btd_adv_client *client, uint8_t status)
 						mgmt_errstr(status), status);
 		reply = btd_error_failed(client->reg,
 					"Failed to register advertisement");
-		queue_remove(client->manager->clients, client);
-		g_idle_add(client_free_idle_cb, client);
 
 	} else
 		reply = dbus_message_new_method_return(client->reg);
@@ -972,6 +973,8 @@ static void add_client_complete(struct btd_adv_client *client, uint8_t status)
 	g_dbus_send_message(btd_get_dbus_connection(), reply);
 	dbus_message_unref(client->reg);
 	client->reg = NULL;
+
+	client_unref(client);
 }
 
 static void add_adv_callback(uint8_t status, uint16_t length,
@@ -1060,8 +1063,11 @@ static DBusMessage *parse_advertisement(struct btd_adv_client *client)
 	}
 
 	err = refresh_adv(client, add_adv_callback);
-	if (!err)
+	if (!err) {
+		/* Hold reference to client until add_adv_callback is finished */
+		client_ref(client);
 		return NULL;
+	}
 
 fail:
 	return btd_error_failed(client->reg, "Failed to parse advertisement.");
@@ -1082,14 +1088,12 @@ static void client_proxy_added(GDBusProxy *proxy, void *data)
 		return;
 
 	/* Failed to publish for some reason, remove. */
-	queue_remove(client->manager->clients, client);
-
-	g_idle_add(client_free_idle_cb, client);
-
 	g_dbus_send_message(btd_get_dbus_connection(), reply);
 
 	dbus_message_unref(client->reg);
 	client->reg = NULL;
+
+	client_unref(client);
 }
 
 static struct btd_adv_client *client_create(struct btd_adv_manager *manager,
@@ -1189,6 +1193,7 @@ static DBusMessage *register_advertisement(DBusConnection *conn,
 	DBG("Registered advertisement at path %s", match.path);
 
 	queue_push_tail(manager->clients, client);
+	client_ref(client);
 
 	return NULL;
 }
@@ -1218,7 +1223,7 @@ static DBusMessage *unregister_advertisement(DBusConnection *conn,
 	if (!client)
 		return btd_error_does_not_exist(msg);
 
-	client_remove(client);
+	client_unref(client);
 
 	return dbus_message_new_method_return(msg);
 }
-- 
2.7.4