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Message-Id: <20230802033737.9738-1-duoming@zju.edu.cn>
Date: Wed, 2 Aug 2023 11:37:37 +0800
From: Duoming Zhou <duoming@....edu.cn>
To: ysato@...rs.sourceforge.jp
Cc: dalias@...c.org, glaubitz@...sik.fu-berlin.de, kvalo@...nel.org,
pavel@....cz, pabeni@...hat.com, rostedt@...dmis.org,
linux-sh@...r.kernel.org, linux-kernel@...r.kernel.org,
Duoming Zhou <duoming@....edu.cn>
Subject: [PATCH] sh: push-switch: reorder cleanup operations to avoid UAF bug
The original code puts flush_work() before timer_shutdown_sync()
in switch_drv_remove(). Although we use flush_work() to stop
the worker, it could be re-scheduled in switch_timer. As a result,
the UAF bug will happen. The detail is shown below:
(cpu 0) | (cpu 1)
switch_drv_remove() |
flush_work() |
... | switch_timer //timer
| schedule_work(&psw->work)
timer_shutdown_sync() |
... | switch_work_handler //worker
kfree(psw) //free |
| psw->state = 0 //use
This patch puts timer_shutdown_sync() before flush_work() to
mitigate the bugs. As a result, the worker and timer could
be stopped safely before the deallocate operations.
Fixes: 9f5e8eee5cfe ("sh: generic push-switch framework.")
Signed-off-by: Duoming Zhou <duoming@....edu.cn>
---
arch/sh/drivers/push-switch.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/sh/drivers/push-switch.c b/arch/sh/drivers/push-switch.c
index c95f48ff3f6..6ecba5f521e 100644
--- a/arch/sh/drivers/push-switch.c
+++ b/arch/sh/drivers/push-switch.c
@@ -101,8 +101,8 @@ static int switch_drv_remove(struct platform_device *pdev)
device_remove_file(&pdev->dev, &dev_attr_switch);
platform_set_drvdata(pdev, NULL);
- flush_work(&psw->work);
timer_shutdown_sync(&psw->debounce);
+ flush_work(&psw->work);
free_irq(irq, pdev);
kfree(psw);
--
2.17.1
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