at91_adc_interrupt can call at91_adc_touch_data_handler function
to start the work by schedule_work(&st->touch_st.workq).
If we remove the module which will call at91_adc_remove to
make cleanup, it will free indio_dev through iio_device_unregister
while the work mentioned above will be used. The sequence of operations
that may lead to a UAF bug is as follows:
CPU0 CPU1
| at91_adc_workq_handler
at91_adc_remove |
iio_device_unregister(indio_dev) |
device_release |
//free indio_dev |
| iio_push_to_buffers(indio_dev)
| //use indio_dev
Fix it by ensuring that the work is canceled before proceeding with
the cleanup in at91_adc_remove.
Fixes: 27e177190891 ("iio:adc:at91_adc8xx: introduce new atmel adc driver")
Signed-off-by: Pei Xiao <xiaopei01@xxxxxxxxxx>
---
drivers/iio/adc/at91-sama5d2_adc.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index 8e5aaf15a921..4ba52b500054 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -2491,6 +2491,7 @@ static void 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);
+ cancel_work_sync(&st->touch_st.workq);
iio_device_unregister(indio_dev);
at91_adc_dma_disable(st);
--
2.34.1
