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Commit c949c224 authored by Peter Hurley's avatar Peter Hurley Committed by Marcel Holtmann
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Bluetooth: Fix RFCOMM tty teardown race 



RFCOMM tty device teardown can race with new tty device registration
for the same device id:

CPU 0                           | CPU 1
rfcomm_dev_add                  | rfcomm_dev_destruct
                                |   spin_lock
                                |   list_del   <== dev_id no longer used
                                |   spin_unlock
  spin_lock                     |     .
  [search rfcomm_dev_list]      |     .
  [dev_id not in use]           |     .
  [initialize new rfcomm_dev]   |     .
  spin_unlock                   |     .
                                |     .
  tty_port_register_device      |   tty_unregister_device

Don't remove rfcomm_dev from the device list until after tty device
unregistration has completed.

Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Tested-By: default avatarAlexander Holler <holler@ahsoftware.de>
Signed-off-by: default avatarMarcel Holtmann <marcel@holtmann.org>
parent 80ea7337

net/bluetooth/rfcomm/tty.c

+4 −4
Original line number Diff line number Diff line
@@ -84,10 +84,6 @@ static void rfcomm_dev_destruct(struct tty_port *port) 


	BT_DBG("dev %p dlc %p", dev, dlc);



	spin_lock(&rfcomm_dev_lock);

	list_del(&dev->list);

	spin_unlock(&rfcomm_dev_lock);



	rfcomm_dlc_lock(dlc);

	/* Detach DLC if it's owned by this dev */

	if (dlc->owner == dev)
@@ -98,6 +94,10 @@ static void rfcomm_dev_destruct(struct tty_port *port) 


	tty_unregister_device(rfcomm_tty_driver, dev->id);



	spin_lock(&rfcomm_dev_lock);

	list_del(&dev->list);

	spin_unlock(&rfcomm_dev_lock);



	kfree(dev);



	/* It's safe to call module_put() here because socket still