linux-kernel - [PATCH v3] iio: adc: at91-sama5d2_adc: Fix potential use-after-free in sama5d2

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Message-Id: <90dec520a9537af2feab9d56b22d99878fba9e2a.1761705396.git.xiaopei01@kylinos.cn>
Date: Wed, 29 Oct 2025 10:40:16 +0800
From: Pei Xiao <xiaopei01@...inos.cn>
To: jic23@...nel.org,
	linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	eugen.hristev@...aro.org
Cc: Pei Xiao <xiaopei01@...inos.cn>
Subject: [PATCH v3] iio: adc: at91-sama5d2_adc: Fix potential use-after-free in sama5d2_adc driver

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 but
quite a bit later. 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)     |
//free indio_dev a bit later         |
                                     | 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: 3ec2774f1cc ("iio: adc: at91-sama5d2_adc: add support for position and pressure channels")
Signed-off-by: Pei Xiao <xiaopei01@...inos.cn>
---
changlog in v3: move cancel_work_sync after iio_device_unregister
changlog in v2: use correct Fix id
---
 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 b4c36e6a7490..aa4ba3f5a506 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -2481,6 +2481,7 @@ static void at91_adc_remove(struct platform_device *pdev)
 	struct at91_adc_state *st = iio_priv(indio_dev);
 
 	iio_device_unregister(indio_dev);
+	cancel_work_sync(&st->touch_st.workq);
 
 	at91_adc_dma_disable(st);
 
-- 
2.25.1