linux-kernel - Re: [PATCH] drivers: watchdog: rdc321x

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Date:   Fri, 7 Aug 2020 09:21:41 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     madhuparnabhowmik10@...il.com
Cc:     wim@...ux-watchdog.org, linux-watchdog@...r.kernel.org,
        linux-kernel@...r.kernel.org, andrianov@...ras.ru,
        ldv-project@...uxtesting.org, f.fainelli@...il.com
Subject: Re: [PATCH] drivers: watchdog: rdc321x_wdt: Fix race condition bugs

On Fri, Aug 07, 2020 at 04:59:02PM +0530, madhuparnabhowmik10@...il.com wrote:
> From: Madhuparna Bhowmik <madhuparnabhowmik10@...il.com>
> 
> 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@...il.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

Having said that ... this is yet another potentially obsolete driver.
You are really wasting your (and, fwiw, my) time.

Florian, any thoughts if support for this chip can/should be deprecated
or even removed ?

Guenter

> ---
>  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 57187efeb86f..f0c94ea51c3e 100644
> --- a/drivers/watchdog/rdc321x_wdt.c
> +++ b/drivers/watchdog/rdc321x_wdt.c
> @@ -231,6 +231,8 @@ 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) {
> @@ -245,14 +247,11 @@ 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);
>  
>  	timer_setup(&rdc321x_wdt_device.timer, rdc321x_wdt_trigger, 0);
>  
> -	rdc321x_wdt_device.default_ticks = ticks;
> -
>  	dev_info(&pdev->dev, "watchdog init success\n");
>  
>  	return 0;
> -- 
> 2.17.1
>