[PATCH] media: siano: initialise the urb work once, not on every completion

[Yogesh Gaur]

smsusb_onresponse() re-runs INIT_WORK() on surb->wq every time an URB
completes, right before scheduling it.  INIT_WORK() resets work->data,
which is where the workqueue keeps the work's state, including the
"being cancelled" mark that cancel_work_sync() sets while it waits.

smsusb_stop_streaming() kills the URB and then cancels the work.  If
do_submit_urb() is running at that point it can resubmit the URB, and
if that URB completes during the cancel, smsusb_onresponse()
re-initialises the work, wiping the cancel mark, and queues it again.
__flush_work() then finds a queued work where it expects an idle one:

  smsusb:smsusb_init_device: smscore_start_device(...) failed
  data & WORK_STRUCT_PWQ
  WARNING: kernel/workqueue.c:4425 at __flush_work+0xc8f/0xd70 kernel/workqueue.c:4425
   __cancel_work_sync+0xbf/0x110 kernel/workqueue.c:4568
   smsusb_stop_streaming drivers/media/usb/siano/smsusb.c:183 [inline]
   smsusb_term_device+0xdd/0x3d0 drivers/media/usb/siano/smsusb.c:345
   smsusb_init_device drivers/media/usb/siano/smsusb.c:497 [inline]
   smsusb_probe+0x1aba/0x2280 drivers/media/usb/siano/smsusb.c:575

Initialise each work item once, next to the URB it resubmits, and only
schedule it from the completion handler.  smsusb_stop_streaming() keeps
its wq.func check, which still skips the URBs that were never set up
when smsusb_init_device() fails early.

Fixes: ebad8e731c1c ("media: usb: siano: Fix use after free bugs caused by do_submit_urb")
Reported-by: syzbot+d627b1495de0e851be32@xxxxxxxxxxxxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Assisted-by: LLM
Signed-off-by: Yogesh Gaur <yogeshgaur.83@xxxxxxxxx>
---
Built with W=1 only; not runtime-tested.

 drivers/media/usb/siano/smsusb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/usb/siano/smsusb.c b/drivers/media/usb/siano/smsusb.c
index 0fdc2e0950b7..210c323c8232 100644
--- a/drivers/media/usb/siano/smsusb.c
+++ b/drivers/media/usb/siano/smsusb.c
@@ -143,7 +143,6 @@ static void smsusb_onresponse(struct urb *urb)
 
 
 exit_and_resubmit:
-	INIT_WORK(&surb->wq, do_submit_urb);
 	schedule_work(&surb->wq);
 }
 
@@ -468,6 +467,7 @@ static int smsusb_init_device(struct usb_interface *intf, int board_id)
 	/* initialize urbs */
 	for (i = 0; i < MAX_URBS; i++) {
 		dev->surbs[i].dev = dev;
+		INIT_WORK(&dev->surbs[i].wq, do_submit_urb);
 		dev->surbs[i].urb = usb_alloc_urb(0, GFP_KERNEL);
 		if (!dev->surbs[i].urb)
 			goto err_unregister_device;
-- 
2.55.0.windows.5