linux-kernel - [PATCH v2 3/8] Bluetooth: mgmt: take lock and hold reference when handling hci

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Message-ID: <1ac16b2d328ccef42d09e875c09232bd7f0e32da.1762100290.git.pav@iki.fi>
Date: Sun,  2 Nov 2025 18:19:35 +0200
From: Pauli Virtanen <pav@....fi>
To: linux-bluetooth@...r.kernel.org
Cc: Pauli Virtanen <pav@....fi>,
	marcel@...tmann.org,
	johan.hedberg@...il.com,
	luiz.dentz@...il.com,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/8] Bluetooth: mgmt: take lock and hold reference when handling hci_conn

Take hdev/rcu lock to prevent concurrent deletion of the hci_conn we are
handling.

When using hci_conn* pointers across critical sections, always take
refcount to keep the pointer valid.

For hci_abort_conn() only hold refcount, as the function takes
hdev->lock itself.

Fixes: 227a0cdf4a028 ("Bluetooth: MGMT: Fix not generating command complete for MGMT_OP_DISCONNECT")
Signed-off-by: Pauli Virtanen <pav@....fi>
---

Notes:
    v2:
    - no change

 net/bluetooth/mgmt.c | 42 ++++++++++++++++++++++++++++++++++++++----
 1 file changed, 38 insertions(+), 4 deletions(-)

diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 78b7af8bf45f..535c475c2d25 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -3081,6 +3081,8 @@ static int unpair_device_sync(struct hci_dev *hdev, void *data)
 	struct mgmt_cp_unpair_device *cp = cmd->param;
 	struct hci_conn *conn;
 
+	rcu_read_lock();
+
 	if (cp->addr.type == BDADDR_BREDR)
 		conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK,
 					       &cp->addr.bdaddr);
@@ -3088,6 +3090,11 @@ static int unpair_device_sync(struct hci_dev *hdev, void *data)
 		conn = hci_conn_hash_lookup_le(hdev, &cp->addr.bdaddr,
 					       le_addr_type(cp->addr.type));
 
+	if (conn)
+		hci_conn_get(conn);
+
+	rcu_read_unlock();
+
 	if (!conn)
 		return 0;
 
@@ -3095,6 +3102,7 @@ static int unpair_device_sync(struct hci_dev *hdev, void *data)
 	 * will clean up the connection no matter the error.
 	 */
 	hci_abort_conn(conn, HCI_ERROR_REMOTE_USER_TERM);
+	hci_conn_put(conn);
 
 	return 0;
 }
@@ -3242,6 +3250,8 @@ static int disconnect_sync(struct hci_dev *hdev, void *data)
 	struct mgmt_cp_disconnect *cp = cmd->param;
 	struct hci_conn *conn;
 
+	rcu_read_lock();
+
 	if (cp->addr.type == BDADDR_BREDR)
 		conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK,
 					       &cp->addr.bdaddr);
@@ -3249,6 +3259,11 @@ static int disconnect_sync(struct hci_dev *hdev, void *data)
 		conn = hci_conn_hash_lookup_le(hdev, &cp->addr.bdaddr,
 					       le_addr_type(cp->addr.type));
 
+	if (conn)
+		hci_conn_get(conn);
+
+	rcu_read_unlock();
+
 	if (!conn)
 		return -ENOTCONN;
 
@@ -3256,6 +3271,7 @@ static int disconnect_sync(struct hci_dev *hdev, void *data)
 	 * will clean up the connection no matter the error.
 	 */
 	hci_abort_conn(conn, HCI_ERROR_REMOTE_USER_TERM);
+	hci_conn_put(conn);
 
 	return 0;
 }
@@ -7372,6 +7388,9 @@ static void get_conn_info_complete(struct hci_dev *hdev, void *data, int err)
 		rp.max_tx_power = HCI_TX_POWER_INVALID;
 	}
 
+	if (conn)
+		hci_conn_put(conn);
+
 	mgmt_cmd_complete(cmd->sk, cmd->hdev->id, MGMT_OP_GET_CONN_INFO, status,
 			  &rp, sizeof(rp));
 
@@ -7386,6 +7405,8 @@ static int get_conn_info_sync(struct hci_dev *hdev, void *data)
 	int err;
 	__le16   handle;
 
+	hci_dev_lock(hdev);
+
 	/* Make sure we are still connected */
 	if (cp->addr.type == BDADDR_BREDR)
 		conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK,
@@ -7393,12 +7414,16 @@ static int get_conn_info_sync(struct hci_dev *hdev, void *data)
 	else
 		conn = hci_conn_hash_lookup_ba(hdev, LE_LINK, &cp->addr.bdaddr);
 
-	if (!conn || conn->state != BT_CONNECTED)
+	if (!conn || conn->state != BT_CONNECTED) {
+		hci_dev_unlock(hdev);
 		return MGMT_STATUS_NOT_CONNECTED;
+	}
 
-	cmd->user_data = conn;
+	cmd->user_data = hci_conn_get(conn);
 	handle = cpu_to_le16(conn->handle);
 
+	hci_dev_unlock(hdev);
+
 	/* Refresh RSSI each time */
 	err = hci_read_rssi_sync(hdev, handle);
 
@@ -7532,6 +7557,9 @@ static void get_clock_info_complete(struct hci_dev *hdev, void *data, int err)
 	}
 
 complete:
+	if (conn)
+		hci_conn_put(conn);
+
 	mgmt_cmd_complete(cmd->sk, cmd->hdev->id, cmd->opcode, status, &rp,
 			  sizeof(rp));
 
@@ -7548,15 +7576,21 @@ static int get_clock_info_sync(struct hci_dev *hdev, void *data)
 	memset(&hci_cp, 0, sizeof(hci_cp));
 	hci_read_clock_sync(hdev, &hci_cp);
 
+	hci_dev_lock(hdev);
+
 	/* Make sure connection still exists */
 	conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK, &cp->addr.bdaddr);
-	if (!conn || conn->state != BT_CONNECTED)
+	if (!conn || conn->state != BT_CONNECTED) {
+		hci_dev_unlock(hdev);
 		return MGMT_STATUS_NOT_CONNECTED;
+	}
 
-	cmd->user_data = conn;
+	cmd->user_data = hci_conn_get(conn);
 	hci_cp.handle = cpu_to_le16(conn->handle);
 	hci_cp.which = 0x01; /* Piconet clock */
 
+	hci_dev_unlock(hdev);
+
 	return hci_read_clock_sync(hdev, &hci_cp);
 }
 
-- 
2.51.1