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

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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: afba937e54 ("USB: CDC WDM driver")
Cc: stable <stable@kernel.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Link: https://lore.kernel.org/r/20240314115132.3907-1-oneukum@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Oliver Neukum 2024-03-14 12:50:48 +01:00 committed by Greg Kroah-Hartman
parent 5d69a3b54e
commit 339f83612f
1 changed files with 5 additions and 1 deletions
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6
drivers/usb/class/cdc-wdm.c
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@ -485,6 +485,7 @@ out_free_mem:
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);