lkml.org 
[lkml]   [2023]   [Aug]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] sh: push-switch: reorder cleanup operations to avoid UAF bug
Date
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@zju.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
\
 
 \ /
  Last update: 2023-08-02 05:39    [W:0.032 / U:0.108 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site