netdev - [ldv-project] [net] rtl8188ee: a potential race condition

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Date:	Fri, 10 Jun 2016 12:21:32 +0400
From:	Pavel Andrianov <andrianov@...ras.ru>
To:	Larry Finger <Larry.Finger@...inger.net>
CC:	Chaoming Li <chaoming_li@...lsil.com.cn>,
	Kalle Valo <kvalo@...eaurora.org>,
	linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Vaishali Thakkar <vaishali.thakkar@...cle.com>,
	ldv-project@...uxtesting.org
Subject: [ldv-project] [net] rtl8188ee: a potential race condition

Hi!

There is a potential data race in 
drivers/net/wireless/realtek/rtlwifi/rtl8188ee/rtl8188ee.ko.

In the function rtl88ee_gpio_radio_on_off_checking the flag 
ppsc->rfchange_inprogress is set with a spinlock protection. In the 
function rtl_ps_set_rf_state the flag is read also under a spinlock. But 
the function rtl88e_dm_watchdog read it without any locks. As a result 
rtl88e_dm_watchdog may execute the succeeding code while changing (with 
the flag rfchange_inprogress == true). I do not exactly determine the 
consequences, but likely they are not good if there exists such check. 
Could anybody more confident confirm this?

The function rtl_ps_set_rf_state is always called with its parameter 
[protect_or_not == false]. Is this flag really necessary, if the value 
'true' is never used? The function is also set the flag 
ppsc->rfchange_inprogress and may affect the rtl88e_dm_watchdog as in 
the previous case.

-- 
Pavel Andrianov
Linux Verification Center, ISPRAS
web: http://linuxtesting.org
e-mail: andrianov@...ras.ru