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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>,
        Guenter Roeck <linux@roeck-us.net>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Wim Van Sebroeck <wim@linux-watchdog.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 038/117] drivers: watchdog: rdc321x_wdt: Fix race condition bugs
Date:   Mon,  9 Nov 2020 13:54:24 +0100
Message-Id: <20201109125027.460261273@linuxfoundation.org>
In-Reply-To: <20201109125025.630721781@linuxfoundation.org>
References: <20201109125025.630721781@linuxfoundation.org>
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From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>

[ Upstream commit 4b2e7f99cdd314263c9d172bc17193b8b6bba463 ]

In rdc321x_wdt_probe(), rdc321x_wdt_device.queue is initialized
after misc_register(), hence if ioctl is called before its
initialization which can call rdc321x_wdt_start() function,
it will see an uninitialized value of rdc321x_wdt_device.queue,
hence initialize it before misc_register().
Also, rdc321x_wdt_device.default_ticks is accessed in reset()
function called from write callback, thus initialize it before
misc_register().

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20200807112902.28764-1-madhuparnabhowmik10@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/watchdog/rdc321x_wdt.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/watchdog/rdc321x_wdt.c b/drivers/watchdog/rdc321x_wdt.c
index 47a8f1b1087d4..4568af9a165be 100644
--- a/drivers/watchdog/rdc321x_wdt.c
+++ b/drivers/watchdog/rdc321x_wdt.c
@@ -244,6 +244,8 @@ static int rdc321x_wdt_probe(struct platform_device *pdev)
 
 	rdc321x_wdt_device.sb_pdev = pdata->sb_pdev;
 	rdc321x_wdt_device.base_reg = r->start;
+	rdc321x_wdt_device.queue = 0;
+	rdc321x_wdt_device.default_ticks = ticks;
 
 	err = misc_register(&rdc321x_wdt_misc);
 	if (err < 0) {
@@ -258,14 +260,11 @@ static int rdc321x_wdt_probe(struct platform_device *pdev)
 				rdc321x_wdt_device.base_reg, RDC_WDT_RST);
 
 	init_completion(&rdc321x_wdt_device.stop);
-	rdc321x_wdt_device.queue = 0;
 
 	clear_bit(0, &rdc321x_wdt_device.inuse);
 
 	setup_timer(&rdc321x_wdt_device.timer, rdc321x_wdt_trigger, 0);
 
-	rdc321x_wdt_device.default_ticks = ticks;
-
 	dev_info(&pdev->dev, "watchdog init success\n");
 
 	return 0;
-- 
2.27.0