Commit 339f8361 authored by Oliver Neukum's avatar Oliver Neukum Committed by Greg Kroah-Hartman
Browse files

usb: cdc-wdm: close race between read and workqueue 



wdm_read() cannot race with itself. However, in
service_outstanding_interrupt() it can race with the
workqueue, which can be triggered by error handling.

Hence we need to make sure that the WDM_RESPONDING
flag is not just only set but tested.

Fixes: afba937e ("USB: CDC WDM driver")
Cc: stable <stable@kernel.org>
Signed-off-by: default avatarOliver Neukum <oneukum@suse.com>
Link: https://lore.kernel.org/r/20240314115132.3907-1-oneukum@suse.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5d69a3b5

drivers/usb/class/cdc-wdm.c

+5 −1
Original line number Diff line number Diff line
@@ -485,6 +485,7 @@ static ssize_t wdm_write 
static int service_outstanding_interrupt(struct wdm_device *desc)

{

	int rv = 0;

	int used;



	/* submit read urb only if the device is waiting for it */

	if (!desc->resp_count || !--desc->resp_count)
@@ -499,7 +500,10 @@ static int service_outstanding_interrupt(struct wdm_device *desc) 
		goto out;

	}



	set_bit(WDM_RESPONDING, &desc->flags);

	used = test_and_set_bit(WDM_RESPONDING, &desc->flags);

	if (used)

		goto out;



	spin_unlock_irq(&desc->iuspin);

	rv = usb_submit_urb(desc->response, GFP_KERNEL);

	spin_lock_irq(&desc->iuspin);