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Subject[PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition
Date
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);
iio_device_unregister(indio_dev);

at91_adc_dma_disable(st);
--
2.25.1
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