linux-kernel - Re: [ldv-project] [PATCH] drivers: watchdog: rdc321x_wdt: Fix race condition bugs

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Message-Id: <507311596824581@mail.yandex.ru>
Date:   Fri, 07 Aug 2020 21:30:58 +0300
From:   Evgeny Novikov <novikov@...ras.ru>
To:     Guenter Roeck <linux@...ck-us.net>,
        "madhuparnabhowmik10@...il.com" <madhuparnabhowmik10@...il.com>
Cc:     "ldv-project@...uxtesting.org" <ldv-project@...uxtesting.org>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "wim@...ux-watchdog.org" <wim@...ux-watchdog.org>
Subject: Re: [ldv-project] [PATCH] drivers: watchdog: rdc321x_wdt: Fix race condition bugs

07.08.2020, 19:21, "Guenter Roeck" <linux@...ck-us.net>:
> 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.

Static analysis tools are not aware about obsolete drivers.
It would be great if there will be some formal way to filter them out.
Maybe some file will enumerate all obsolete drivers, or there will be
something within their source code, or something else.

-- 
Best regards,
Evgeny Novikov

>
> 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
>
> _______________________________________________
> ldv-project mailing list
> ldv-project@...uxtesting.org
> http://linuxtesting.org/cgi-bin/mailman/listinfo/ldv-project

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