[PATCH 4.17 098/336] mwifiex: handle race during mwifiex_usb_disconnect

From: Greg Kroah-Hartman
Date: Wed Aug 01 2018 - 14:26:53 EST

4.17-stable review patch. If anyone has any objections, please let me know.


From: Ganapathi Bhat <gbhat@xxxxxxxxxxx>

[ Upstream commit b817047ae70c0bd67b677b65d0d69d72cd6e9728 ]

Race condition is observed during rmmod of mwifiex_usb:

1. The rmmod thread will call mwifiex_usb_disconnect(), download
SHUTDOWN command and do wait_event_interruptible_timeout(),
waiting for response.

2. The main thread will handle the response and will do a
wake_up_interruptible(), unblocking rmmod thread.

3. On getting unblocked, rmmod thread will make rx_cmd.urb = NULL in

4. The main thread will try to resubmit rx_cmd.urb in
mwifiex_usb_submit_rx_urb(), which is NULL.

To fix, wait for main thread to complete before calling

Signed-off-by: Ganapathi Bhat <gbhat@xxxxxxxxxxx>
Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
drivers/net/wireless/marvell/mwifiex/usb.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/net/wireless/marvell/mwifiex/usb.c
+++ b/drivers/net/wireless/marvell/mwifiex/usb.c
@@ -644,6 +644,9 @@ static void mwifiex_usb_disconnect(struc

+ if (adapter->workqueue)
+ flush_workqueue(adapter->workqueue);

mwifiex_dbg(adapter, FATAL,