From: Jesse Melhuish <melhuishj@chromium.org>
Date: Mon, 15 Nov 2021 22:00:52 +0000
Subject: Bluetooth: Don't initialize msft/aosp when using user channel
Patch-mainline: v5.17-rc1
Git-commit: 385315decf65902768a0062b4e594f59f013025e
References: jsc#PED-1407

A race condition is triggered when usermode control is given to
userspace before the kernel's MSFT query responds, resulting in an
unexpected response to userspace's reset command.

Issue can be observed in btmon:

< HCI Command: Vendor (0x3f|0x001e) plen 2                    #3 [hci0]
        05 01                                            ..
@ USER Open: bt_stack_manage (privileged) version 2.22  {0x0002} [hci0]
< HCI Command: Reset (0x03|0x0003) plen 0                     #4 [hci0]
> HCI Event: Command Complete (0x0e) plen 5                   #5 [hci0]
      Vendor (0x3f|0x001e) ncmd 1
	Status: Command Disallowed (0x0c)
	05                                               .
> HCI Event: Command Complete (0x0e) plen 4                   #6 [hci0]
      Reset (0x03|0x0003) ncmd 2
	Status: Success (0x00)

Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Reviewed-by: Sonny Sasaka <sonnysasaka@chromium.org>
Signed-off-by: Jesse Melhuish <melhuishj@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
 net/bluetooth/hci_sync.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -3887,8 +3887,10 @@ setup_failed:
 	    hci_dev_test_flag(hdev, HCI_VENDOR_DIAG) && hdev->set_diag)
 		ret = hdev->set_diag(hdev, true);
 
-	msft_do_open(hdev);
-	aosp_do_open(hdev);
+	if (!hci_dev_test_flag(hdev, HCI_USER_CHANNEL)) {
+		msft_do_open(hdev);
+		aosp_do_open(hdev);
+	}
 
 	clear_bit(HCI_INIT, &hdev->flags);
 
@@ -4031,8 +4033,10 @@ int hci_dev_close_sync(struct hci_dev *h
 
 	hci_sock_dev_event(hdev, HCI_DEV_DOWN);
 
-	aosp_do_close(hdev);
-	msft_do_close(hdev);
+	if (!hci_dev_test_flag(hdev, HCI_USER_CHANNEL)) {
+		aosp_do_close(hdev);
+		msft_do_close(hdev);
+	}
 
 	if (hdev->flush)
 		hdev->flush(hdev);