Patch "Bluetooth: hci_sync: add lock to protect HCI_UNREGISTER" has been added to the 6.3-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    Bluetooth: hci_sync: add lock to protect HCI_UNREGISTER

to the 6.3-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     bluetooth-hci_sync-add-lock-to-protect-hci_unregiste.patch
and it can be found in the queue-6.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 1036271d82e6b3d698e5b7f85384b497fcbd2653
Author: Zhengping Jiang <jiangzp@xxxxxxxxxx>
Date:   Wed May 24 17:11:58 2023 -0700

    Bluetooth: hci_sync: add lock to protect HCI_UNREGISTER
    
    [ Upstream commit 1857c19941c87eb36ad47f22a406be5dfe5eff9f ]
    
    When the HCI_UNREGISTER flag is set, no jobs should be scheduled. Fix
    potential race when HCI_UNREGISTER is set after the flag is tested in
    hci_cmd_sync_queue.
    
    Fixes: 0b94f2651f56 ("Bluetooth: hci_sync: Fix queuing commands when HCI_UNREGISTER is set")
    Signed-off-by: Zhengping Jiang <jiangzp@xxxxxxxxxx>
    Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 86db7f3a31ce5..b973ecb222f65 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -514,6 +514,7 @@ struct hci_dev {
 	struct work_struct	cmd_sync_work;
 	struct list_head	cmd_sync_work_list;
 	struct mutex		cmd_sync_work_lock;
+	struct mutex		unregister_lock;
 	struct work_struct	cmd_sync_cancel_work;
 	struct work_struct	reenable_adv_work;
 
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 334e308451f53..ac36e7ae70b21 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2685,7 +2685,9 @@ void hci_unregister_dev(struct hci_dev *hdev)
 {
 	BT_DBG("%p name %s bus %d", hdev, hdev->name, hdev->bus);
 
+	mutex_lock(&hdev->unregister_lock);
 	hci_dev_set_flag(hdev, HCI_UNREGISTER);
+	mutex_unlock(&hdev->unregister_lock);
 
 	write_lock(&hci_dev_list_lock);
 	list_del(&hdev->list);
diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index b65ee3a32e5d7..fd3b6d79a7f8b 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -629,6 +629,7 @@ void hci_cmd_sync_init(struct hci_dev *hdev)
 	INIT_WORK(&hdev->cmd_sync_work, hci_cmd_sync_work);
 	INIT_LIST_HEAD(&hdev->cmd_sync_work_list);
 	mutex_init(&hdev->cmd_sync_work_lock);
+	mutex_init(&hdev->unregister_lock);
 
 	INIT_WORK(&hdev->cmd_sync_cancel_work, hci_cmd_sync_cancel_work);
 	INIT_WORK(&hdev->reenable_adv_work, reenable_adv);
@@ -688,14 +689,19 @@ int hci_cmd_sync_queue(struct hci_dev *hdev, hci_cmd_sync_work_func_t func,
 		       void *data, hci_cmd_sync_work_destroy_t destroy)
 {
 	struct hci_cmd_sync_work_entry *entry;
+	int err = 0;
 
-	if (hci_dev_test_flag(hdev, HCI_UNREGISTER))
-		return -ENODEV;
+	mutex_lock(&hdev->unregister_lock);
+	if (hci_dev_test_flag(hdev, HCI_UNREGISTER)) {
+		err = -ENODEV;
+		goto unlock;
+	}
 
 	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
-	if (!entry)
-		return -ENOMEM;
-
+	if (!entry) {
+		err = -ENOMEM;
+		goto unlock;
+	}
 	entry->func = func;
 	entry->data = data;
 	entry->destroy = destroy;
@@ -706,7 +712,9 @@ int hci_cmd_sync_queue(struct hci_dev *hdev, hci_cmd_sync_work_func_t func,
 
 	queue_work(hdev->req_workqueue, &hdev->cmd_sync_work);
 
-	return 0;
+unlock:
+	mutex_unlock(&hdev->unregister_lock);
+	return err;
 }
 EXPORT_SYMBOL(hci_cmd_sync_queue);