From: Lars-Peter Clausen <lars@metafoo.de>
To: Jonathan Cameron <jic23@kernel.org>, Zheng Wang <zyytlz.wz@163.com>
Cc: alexandre.belloni@bootlin.com, linux-iio@vger.kernel.org,
eugen.hristev@collabora.com, linux-kernel@vger.kernel.org,
claudiu.beznea@microchip.com,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition
Date: Sat, 18 Mar 2023 10:36:04 -0700 [thread overview]
Message-ID: <d62ece80-4d88-36a6-9561-fa0f5afc40c1@metafoo.de> (raw)
In-Reply-To: <20230318173913.19e8a1b1@jic23-huawei>
On 3/18/23 10:39, Jonathan Cameron wrote:
> On Fri, 10 Mar 2023 17:12:39 +0800
> Zheng Wang <zyytlz.wz@163.com> wrote:
>
>> In at91_adc_probe, &st->touch_st.workq is bound with
>> at91_adc_workq_handler. Then it will be started by irq
>> handler at91_adc_touch_data_handler
>>
>> If we remove the driver which will call at91_adc_remove
>> to make cleanup, there may be a unfinished work.
>>
>> The possible sequence is as follows:
>>
>> Fix it by finishing the work before cleanup in the at91_adc_remove
>>
>> CPU0 CPU1
>>
>> |at91_adc_workq_handler
>> at91_adc_remove |
>> iio_device_unregister|
>> iio_dev_release |
>> kfree(iio_dev_opaque);|
>> |
>> |iio_push_to_buffers
>> |&iio_dev_opaque->buffer_list
>> |//use
>> Fixes: 23ec2774f1cc ("iio: adc: at91-sama5d2_adc: add support for position and pressure channels")
>> Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
>> ---
>> drivers/iio/adc/at91-sama5d2_adc.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
>> index 50d02e5fc6fc..1b95d18d9e0b 100644
>> --- a/drivers/iio/adc/at91-sama5d2_adc.c
>> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
>> @@ -2495,6 +2495,8 @@ static int at91_adc_remove(struct platform_device *pdev)
>> struct iio_dev *indio_dev = platform_get_drvdata(pdev);
>> struct at91_adc_state *st = iio_priv(indio_dev);
>>
>> + disable_irq_nosync(st->irq);
>> + cancel_work_sync(&st->touch_st.workq);
> I'd like some input form someone more familiar with this driver than I am.
>
> In particular, whilst it fixes the bug seen I'm not sure what the most
> logical ordering for the disable is or the best way to do it.
>
> I'd prefer to see the irq cut off at source by disabling it at the device
> feature that is generating the irq followed by cancelling or waiting for
> completion of any in flight work.
The usually way you'd do this by calling free_irq() before the
cancel_work_sync().
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next prev parent reply other threads:[~2023-03-18 17:37 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-10 9:12 [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition Zheng Wang
2023-03-18 17:39 ` Jonathan Cameron
2023-03-18 17:36 ` Lars-Peter Clausen [this message]
2023-03-19 15:22 ` Jonathan Cameron
2023-03-20 3:54 ` 王征
2023-03-20 3:41 ` 王征
2023-03-20 3:40 ` 王征
2023-03-20 9:35 ` Nicolas Ferre
2023-03-20 12:07 ` 王征
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