From: 王征 <zyytlz.wz@163.com>
To: "Jonathan Cameron" <jic23@kernel.org>
Cc: alexandre.belloni@bootlin.com, lars@metafoo.de,
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:Re: [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition
Date: Mon, 20 Mar 2023 11:40:28 +0800 (CST) [thread overview]
Message-ID: <6c72d3e3.4dde.186fd1aa9d7.Coremail.zyytlz.wz@163.com> (raw)
In-Reply-To: <20230318173913.19e8a1b1@jic23-huawei>
At 2023-03-19 00:39:13, "Jonathan Cameron" <jic23@kernel.org> 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.
Hi,
Sorry for my late reply. I think we need to replace disable_irq_nosync with free_irq.
Thanks,
Zheng
>
>> iio_device_unregister(indio_dev);
>>
>> at91_adc_dma_disable(st);
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next prev parent reply other threads:[~2023-03-20 3:59 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
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 [this message]
2023-03-20 9:35 ` Nicolas Ferre
2023-03-20 12:07 ` 王征
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