5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Oliver Neukum oneukum@suse.com
commit 339f83612f3a569b194680768b22bf113c26a29d upstream.
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: afba937e540c9 ("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 --- drivers/usb/class/cdc-wdm.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- a/drivers/usb/class/cdc-wdm.c +++ b/drivers/usb/class/cdc-wdm.c @@ -471,6 +471,7 @@ 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) @@ -485,7 +486,10 @@ static int service_outstanding_interrupt 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);