Bluetooth: hci_event: fix potential UAF in hci_le_remote_conn_param_req_evt

hci_conn lookup and field access must be covered by hdev lock in
hci_le_remote_conn_param_req_evt, otherwise it's possible it is freed
concurrently.

Extend the hci_dev_lock critical section to cover all conn usage.

Fixes: 95118dd ("Bluetooth: hci_event: Use of a function table to handle LE subevents")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

Author: pv

net/bluetooth/hci_event.c

@@ -6784,25 +6784,31 @@ static void hci_le_remote_conn_param_req_evt(struct hci_dev *hdev, void *data,
 	latency = le16_to_cpu(ev->latency);
 	timeout = le16_to_cpu(ev->timeout);
 
+	hci_dev_lock(hdev);
+
 	hcon = hci_conn_hash_lookup_handle(hdev, handle);
-	if (!hcon || hcon->state != BT_CONNECTED)
-		return send_conn_param_neg_reply(hdev, handle,
-						 HCI_ERROR_UNKNOWN_CONN_ID);
+	if (!hcon || hcon->state != BT_CONNECTED) {
+		send_conn_param_neg_reply(hdev, handle,
+					  HCI_ERROR_UNKNOWN_CONN_ID);
+		goto unlock;
+	}
 
-	if (max > hcon->le_conn_max_interval)
-		return send_conn_param_neg_reply(hdev, handle,
-						 HCI_ERROR_INVALID_LL_PARAMS);
+	if (max > hcon->le_conn_max_interval) {
+		send_conn_param_neg_reply(hdev, handle,
+					  HCI_ERROR_INVALID_LL_PARAMS);
+		goto unlock;
+	}
 
-	if (hci_check_conn_params(min, max, latency, timeout))
-		return send_conn_param_neg_reply(hdev, handle,
-						 HCI_ERROR_INVALID_LL_PARAMS);
+	if (hci_check_conn_params(min, max, latency, timeout)) {
+		send_conn_param_neg_reply(hdev, handle,
+					  HCI_ERROR_INVALID_LL_PARAMS);
+		goto unlock;
+	}
 
 	if (hcon->role == HCI_ROLE_MASTER) {
 		struct hci_conn_params *params;
 		u8 store_hint;
 
-		hci_dev_lock(hdev);
-
 		params = hci_conn_params_lookup(hdev, &hcon->dst,
 						hcon->dst_type);
 		if (params) {
@@ -6815,8 +6821,6 @@ static void hci_le_remote_conn_param_req_evt(struct hci_dev *hdev, void *data,
 			store_hint = 0x00;
 		}
 
-		hci_dev_unlock(hdev);
-
 		mgmt_new_conn_param(hdev, &hcon->dst, hcon->dst_type,
 				    store_hint, min, max, latency, timeout);
 	}
@@ -6830,6 +6834,9 @@ static void hci_le_remote_conn_param_req_evt(struct hci_dev *hdev, void *data,
 	cp.max_ce_len = 0;
 
 	hci_send_cmd(hdev, HCI_OP_LE_CONN_PARAM_REQ_REPLY, sizeof(cp), &cp);
+
+unlock:
+	hci_dev_unlock(hdev);
 }
 
 static void hci_le_direct_adv_report_evt(struct hci_dev *hdev, void *data,