From: Soenke Huster <soenke.huster@eknoes.de>
Date: Sun, 23 Jan 2022 15:06:24 +0100
Subject: Bluetooth: hci_event: Ignore multiple conn complete events
Patch-mainline: v5.18-rc1
Git-commit: d5ebaa7c5f6f688959e8d40840b2249ede63b8ed
References: jsc#PED-1407

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>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
 include/net/bluetooth/hci_core.h |    3 +
 net/bluetooth/hci_conn.c         |    1 
 net/bluetooth/hci_event.c        |   63 +++++++++++++++++++++++++++++----------
 3 files changed, 52 insertions(+), 15 deletions(-)

--- a/include/net/bluetooth/hci_core.h
+++ b/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
 
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -689,6 +689,7 @@ struct hci_conn *hci_conn_add(struct hci
 
 	bacpy(&conn->dst, dst);
 	bacpy(&conn->src, &hdev->bdaddr);
+	conn->handle = HCI_CONN_HANDLE_UNSET;
 	conn->hdev  = hdev;
 	conn->type  = type;
 	conn->role  = role;
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3068,6 +3068,11 @@ static void hci_conn_complete_evt(struct
 	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
 		}
 	}
 
+	/* 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(s
 		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(s
 			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
 	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
 		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