Bluetooth: hci_event: Ignore multiple conn complete events

When one of the three connection complete events is received multiple
times for the same handle, the device is registered multiple times which
leads to memory corruptions. Therefore, consequent events for a single
connection are ignored.

The conn->state can hold different values, therefore HCI_CONN_HANDLE_UNSET
is introduced to identify new connections. To make sure the events do not
contain this or another invalid handle HCI_CONN_HANDLE_MAX and checks
are introduced.

Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=215497
Signed-off-by: Soenke Huster <soenke.huster@eknoes.de>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

Author: eknoes

include/net/bluetooth/hci_core.h

@@ -303,6 +303,9 @@ struct adv_monitor {
 
 #define HCI_MAX_SHORT_NAME_LENGTH	10
 
+#define HCI_CONN_HANDLE_UNSET		0xffff
+#define HCI_CONN_HANDLE_MAX		0x0eff
+
 /* Min encryption key size to match with SMP */
 #define HCI_MIN_ENC_KEY_SIZE		7
 

net/bluetooth/hci_conn.c

@@ -689,6 +689,7 @@ struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst,
 
 	bacpy(&conn->dst, dst);
 	bacpy(&conn->src, &hdev->bdaddr);
+	conn->handle = HCI_CONN_HANDLE_UNSET;
 	conn->hdev  = hdev;
 	conn->type  = type;
 	conn->role  = role;

net/bluetooth/hci_event.c

@@ -3068,6 +3068,11 @@ static void hci_conn_complete_evt(struct hci_dev *hdev, void *data,
 	struct hci_ev_conn_complete *ev = data;
 	struct hci_conn *conn;
 
+	if (__le16_to_cpu(ev->handle) > HCI_CONN_HANDLE_MAX) {
+		bt_dev_err(hdev, "Ignoring HCI_Connection_Complete for invalid handle");
+		return;
+	}
+
 	bt_dev_dbg(hdev, "status 0x%2.2x", ev->status);
 
 	hci_dev_lock(hdev);
@@ -3106,6 +3111,17 @@ static void hci_conn_complete_evt(struct hci_dev *hdev, void *data,
 		}
 	}
 
+	/* The HCI_Connection_Complete event is only sent once per connection.
+	 * Processing it more than once per connection can corrupt kernel memory.
+	 *
+	 * As the connection handle is set here for the first time, it indicates
+	 * whether the connection is already set up.
+	 */
+	if (conn->handle != HCI_CONN_HANDLE_UNSET) {
+		bt_dev_err(hdev, "Ignoring HCI_Connection_Complete for existing connection");
+		goto unlock;
+	}
+
 	if (!ev->status) {
 		conn->handle = __le16_to_cpu(ev->handle);
 
@@ -4674,6 +4690,11 @@ static void hci_sync_conn_complete_evt(struct hci_dev *hdev, void *data,
 		return;
 	}
 
+	if (__le16_to_cpu(ev->handle) > HCI_CONN_HANDLE_MAX) {
+		bt_dev_err(hdev, "Ignoring HCI_Sync_Conn_Complete for invalid handle");
+		return;
+	}
+
 	bt_dev_dbg(hdev, "status 0x%2.2x", ev->status);
 
 	hci_dev_lock(hdev);
@@ -4697,23 +4718,19 @@ static void hci_sync_conn_complete_evt(struct hci_dev *hdev, void *data,
 			goto unlock;
 	}
 
+	/* The HCI_Synchronous_Connection_Complete event is only sent once per connection.
+	 * Processing it more than once per connection can corrupt kernel memory.
+	 *
+	 * As the connection handle is set here for the first time, it indicates
+	 * whether the connection is already set up.
+	 */
+	if (conn->handle != HCI_CONN_HANDLE_UNSET) {
+		bt_dev_err(hdev, "Ignoring HCI_Sync_Conn_Complete event for existing connection");
+		goto unlock;
+	}
+
 	switch (ev->status) {
 	case 0x00:
-		/* The synchronous connection complete event should only be
-		 * sent once per new connection. Receiving a successful
-		 * complete event when the connection status is already
-		 * BT_CONNECTED means that the device is misbehaving and sent
-		 * multiple complete event packets for the same new connection.
-		 *
-		 * Registering the device more than once can corrupt kernel
-		 * memory, hence upon detecting this invalid event, we report
-		 * an error and ignore the packet.
-		 */
-		if (conn->state == BT_CONNECTED) {
-			bt_dev_err(hdev, "Ignoring connect complete event for existing connection");
-			goto unlock;
-		}
-
 		conn->handle = __le16_to_cpu(ev->handle);
 		conn->state  = BT_CONNECTED;
 		conn->type   = ev->link_type;
@@ -5509,6 +5526,11 @@ static void le_conn_complete_evt(struct hci_dev *hdev, u8 status,
 	struct smp_irk *irk;
 	u8 addr_type;
 
+	if (handle > HCI_CONN_HANDLE_MAX) {
+		bt_dev_err(hdev, "Ignoring HCI_LE_Connection_Complete for invalid handle");
+		return;
+	}
+
 	hci_dev_lock(hdev);
 
 	/* All controllers implicitly stop advertising in the event of a
@@ -5550,6 +5572,17 @@ static void le_conn_complete_evt(struct hci_dev *hdev, u8 status,
 		cancel_delayed_work(&conn->le_conn_timeout);
 	}
 
+	/* The HCI_LE_Connection_Complete event is only sent once per connection.
+	 * Processing it more than once per connection can corrupt kernel memory.
+	 *
+	 * As the connection handle is set here for the first time, it indicates
+	 * whether the connection is already set up.
+	 */
+	if (conn->handle != HCI_CONN_HANDLE_UNSET) {
+		bt_dev_err(hdev, "Ignoring HCI_Connection_Complete for existing connection");
+		goto unlock;
+	}
+
 	le_conn_update_addr(conn, bdaddr, bdaddr_type, local_rpa);
 
 	/* Lookup the identity address from the stored connection