Bluetooth: MGMT: revalidate LOAD_CONN_PARAM queued update

MGMT_OP_LOAD_CONN_PARAM queues conn_update_sync() when a single parameter
update changes an existing LE central connection. The queued work currently
stores a borrowed hci_conn_params entry from hdev->le_conn_params. A later
LOAD_CONN_PARAM request can clear disabled parameters and free that entry
before hci_cmd_sync_work() runs the queued callback.

Do not keep the borrowed hci_conn_params pointer in queued work. Queue the
hci_conn instead and hold a reference until the queued callback completes.
When the work runs, revalidate that the connection is still present, look
up the current hci_conn_params entry, and cancel the update if userspace
removed that entry while the work was pending.

Copy the interval values from the current params entry under hdev->lock,
then drop the lock and keep using hci_le_conn_update_sync() to issue the
update.

Validation reproduced this kernel report:
BUG: KASAN: slab-use-after-free in conn_update_sync+0x2a/0xf0 [bluetooth]
Read of size 1 at addr ffff88810c697126 by task kworker/u17:0/377
Workqueue: hci0 hci_cmd_sync_work [bluetooth]

Call Trace:
 <TASK>
 dump_stack_lvl+0x66/0xa0
 print_report+0xce/0x5f0
 kasan_report+0xe0/0x110
 conn_update_sync+0x2a/0xf0 [bluetooth]
 hci_cmd_sync_work+0x187/0x210 [bluetooth]
 process_one_work+0x4fd/0xbc0
 worker_thread+0x2d8/0x570
 kthread+0x1ad/0x1f0
 ret_from_fork+0x3c9/0x540
 ret_from_fork_asm+0x1a/0x30

Allocated by task 466:
 hci_conn_params_add+0xa6/0x240 [bluetooth]
 load_conn_param+0x4e1/0x850 [bluetooth]
 hci_sock_sendmsg+0x96b/0xf80 [bluetooth]

Freed by task 474:
 kfree+0x313/0x590
 hci_conn_params_clear_disabled+0x9b/0xc0 [bluetooth]
 load_conn_param+0x4bf/0x850 [bluetooth]
 hci_sock_sendmsg+0x96b/0xf80 [bluetooth]

Fixes: 0ece498c27d8c ("Bluetooth: MGMT: Make MGMT_OP_LOAD_CONN_PARAM update existing connection")
Suggested-by: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Assisted-by: Codex:gpt-5.5
Signed-off-by: Cen Zhang <zzzccc427@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 733a4b70e10c581b6c7864e92df905a0b437ef38..a0a491e5311e10f82eb2abbe576c3f8780c1c2df 100644 (file)
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -7937,14 +7937,36 @@ unlock:
 
 static int conn_update_sync(struct hci_dev *hdev, void *data)
 {
-       struct hci_conn_params *params = data;
-       struct hci_conn *conn;
+       struct hci_conn *conn = data;
+       struct hci_conn_params *params;
+       struct hci_conn_params local = {};
 
-       conn = hci_conn_hash_lookup_le(hdev, &params->addr, params->addr_type);
-       if (!conn)
-               return -ECANCELED;
+       hci_dev_lock(hdev);
+
+       if (!hci_conn_valid(hdev, conn) || conn->role != HCI_ROLE_MASTER)
+               goto cancel;
+
+       params = hci_conn_params_lookup(hdev, &conn->dst, conn->dst_type);
+       if (!params)
+               goto cancel;
+
+       local.conn_min_interval = params->conn_min_interval;
+       local.conn_max_interval = params->conn_max_interval;
+       local.conn_latency = params->conn_latency;
+       local.supervision_timeout = params->supervision_timeout;
 
-       return hci_le_conn_update_sync(hdev, conn, params);
+       hci_dev_unlock(hdev);
+
+       return hci_le_conn_update_sync(hdev, conn, &local);
+
+cancel:
+       hci_dev_unlock(hdev);
+       return -ECANCELED;
+}
+
+static void conn_update_sync_destroy(struct hci_dev *hdev, void *data, int err)
+{
+       hci_conn_put(data);
 }
 
 static int load_conn_param(struct sock *sk, struct hci_dev *hdev, void *data,
@@ -8054,9 +8076,13 @@ static int load_conn_param(struct sock *sk, struct hci_dev *hdev, void *data,
                            (conn->le_conn_min_interval != min ||
                             conn->le_conn_max_interval != max ||
                             conn->le_conn_latency != latency ||
-                            conn->le_supv_timeout != timeout))
-                               hci_cmd_sync_queue(hdev, conn_update_sync,
-                                                  hci_param, NULL);
+                            conn->le_supv_timeout != timeout)) {
+                               hci_conn_get(conn);
+                               if (hci_cmd_sync_queue(hdev, conn_update_sync,
+                                                      conn,
+                                                      conn_update_sync_destroy) < 0)
+                                       hci_conn_put(conn);
+                       }
                }
        }