Commit 84811412 authored Nov 20, 2019 by Prashant Malani Committed by David S. Miller Nov 20, 2019

r8152: Re-order napi_disable in rtl8152_close

Both rtl_work_func_t() and rtl8152_close() call napi_disable().
Since the two calls aren't protected by a lock, if the close
function starts executing before the work function, we can get into a
situation where the napi_disable() function is called twice in
succession (first by rtl8152_close(), then by set_carrier()).

In such a situation, the second call would loop indefinitely, since
rtl8152_close() doesn't call napi_enable() to clear the NAPI_STATE_SCHED
bit.

The rtl8152_close() function in turn issues a
cancel_delayed_work_sync(), and so it would wait indefinitely for the
rtl_work_func_t() to complete. Since rtl8152_close() is called by a
process holding rtnl_lock() which is requested by other processes, this
eventually leads to a system deadlock and crash.

Re-order the napi_disable() call to occur after the work function
disabling and urb cancellation calls are issued.

Change-Id: I6ef0b703fc214998a037a68f722f784e1d07815e
Reported-by: http://crbug.com/1017928


Signed-off-by: Prashant Malani <pmalani@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent b172845a

drivers/net/usb/r8152.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -4283,10 +4283,10 @@ static int rtl8152_close(struct net_device *netdev)
		unregister_pm_notifier(&tp->pm_notifier);
		#endif
		tasklet_disable(&tp->tx_tl);
		napi_disable(&tp->napi);
		clear_bit(WORK_ENABLE, &tp->flags);
		usb_kill_urb(tp->intr_urb);
		cancel_delayed_work_sync(&tp->schedule);
		napi_disable(&tp->napi);
		netif_stop_queue(netdev);

		res = usb_autopm_get_interface(tp->intf);

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