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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 BlueZ 1/2] core/advertising: Fix crash when unregistering advertisement too fast
Date:   Tue, 12 Nov 2019 14:56:34 +0100
Message-Id: <1573566995-8482-1-git-send-email-simon.mikuda@streamunlimited.com>
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Sender: linux-bluetooth-owner@vger.kernel.org
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When advertisement is unregistered during MGMT_OP_ADD_ADVERTISING it will
crash in add_adv_callback because struct btd_adv_client no longer exist.

This is seen also in debug log from bluetoothd:
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)

Signed-off-by: Simon Mikuda <simon.mikuda@streamunlimited.com>
---
 src/advertising.c | 34 ++++++++++++++++++++++++++--------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/src/advertising.c b/src/advertising.c
index 3ed1376..f53c14c 100644
--- a/src/advertising.c
+++ b/src/advertising.c
@@ -73,6 +73,7 @@ struct btd_adv_client {
 	uint16_t discoverable_to;
 	unsigned int to_id;
 	unsigned int disc_to_id;
+	unsigned int add_adv_id;
 	GDBusClient *client;
 	GDBusProxy *proxy;
 	DBusMessage *reg;
@@ -117,6 +118,15 @@ static void client_free(void *data)
 		g_dbus_client_unref(client->client);
 	}
 
+	if (client->reg) {
+		g_dbus_send_message(btd_get_dbus_connection(),
+				dbus_message_new_method_return(client->reg));
+		dbus_message_unref(client->reg);
+	}
+
+	if (client->add_adv_id)
+		mgmt_cancel(client->manager->mgmt, client->add_adv_id);
+
 	if (client->instance)
 		util_clear_uid(&client->manager->instance_bitmap,
 						client->instance);
@@ -765,7 +775,8 @@ static uint8_t *generate_scan_rsp(struct btd_adv_client *client,
 	return bt_ad_generate(client->scan, len);
 }
 
-static int refresh_adv(struct btd_adv_client *client, mgmt_request_func_t func)
+static int refresh_adv(struct btd_adv_client *client, mgmt_request_func_t func,
+						unsigned int *mgmt_id)
 {
 	struct mgmt_cp_add_advertising *cp;
 	uint8_t param_len;
@@ -774,6 +785,7 @@ static int refresh_adv(struct btd_adv_client *client, mgmt_request_func_t func)
 	uint8_t *scan_rsp;
 	size_t scan_rsp_len = -1;
 	uint32_t flags = 0;
+	unsigned int mgmt_ret;
 
 	DBG("Refreshing advertisement: %s", client->path);
 
@@ -822,13 +834,17 @@ static int refresh_adv(struct btd_adv_client *client, mgmt_request_func_t func)
 	free(adv_data);
 	free(scan_rsp);
 
-	if (!mgmt_send(client->manager->mgmt, MGMT_OP_ADD_ADVERTISING,
-				client->manager->mgmt_index, param_len, cp,
-				func, client, NULL)) {
+	mgmt_ret = mgmt_send(client->manager->mgmt, MGMT_OP_ADD_ADVERTISING,
+			client->manager->mgmt_index, param_len, cp,
+			func, client, NULL);
+
+	if (!mgmt_ret) {
 		error("Failed to add Advertising Data");
 		free(cp);
 		return -EINVAL;
 	}
+	if (mgmt_id)
+		*mgmt_id = mgmt_ret;
 
 	free(cp);
 
@@ -845,7 +861,7 @@ static gboolean client_discoverable_timeout(void *user_data)
 
 	bt_ad_clear_flags(client->data);
 
-	refresh_adv(client, NULL);
+	refresh_adv(client, NULL, NULL);
 
 	return FALSE;
 }
@@ -948,7 +964,7 @@ static void properties_changed(GDBusProxy *proxy, const char *name,
 			continue;
 
 		if (parser->func(iter, client)) {
-			refresh_adv(client, NULL);
+			refresh_adv(client, NULL, NULL);
 			break;
 		}
 	}
@@ -980,6 +996,8 @@ static void add_adv_callback(uint8_t status, uint16_t length,
 	struct btd_adv_client *client = user_data;
 	const struct mgmt_rp_add_advertising *rp = param;
 
+	client->add_adv_id = 0;
+
 	if (status)
 		goto done;
 
@@ -1059,7 +1077,7 @@ static DBusMessage *parse_advertisement(struct btd_adv_client *client)
 		goto fail;
 	}
 
-	err = refresh_adv(client, add_adv_callback);
+	err = refresh_adv(client, add_adv_callback, &client->add_adv_id);
 	if (!err)
 		return NULL;
 
@@ -1449,7 +1467,7 @@ void btd_adv_manager_destroy(struct btd_adv_manager *manager)
 
 static void manager_refresh(void *data, void *user_data)
 {
-	refresh_adv(data, user_data);
+	refresh_adv(data, user_data, NULL);
 }
 
 void btd_adv_manager_refresh(struct btd_adv_manager *manager)
-- 
2.7.4