linux/arch/sh/drivers/push-switch.c
Duoming Zhou 246f80a0b1 sh: push-switch: Reorder cleanup operations to avoid use-after-free 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 rescheduled in switch_timer(). As a result,
a use-after-free bug can occur. The details are 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 will be
stopped safely before the deallocate operations.

Fixes: 9f5e8eee5c ("sh: generic push-switch framework.")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: https://lore.kernel.org/r/20230802033737.9738-1-duoming@zju.edu.cn
Signed-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
2023-09-09 21:54:20 +02:00

137 lines
2.9 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Generic push-switch framework
*
* Copyright (C) 2006 Paul Mundt
*/
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <asm/push-switch.h>
#define DRV_NAME "push-switch"
#define DRV_VERSION "0.1.1"
static ssize_t switch_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct push_switch_platform_info *psw_info = dev->platform_data;
return sprintf(buf, "%s\n", psw_info->name);
}
static DEVICE_ATTR_RO(switch);
static void switch_timer(struct timer_list *t)
{
struct push_switch *psw = from_timer(psw, t, debounce);
schedule_work(&psw->work);
}
static void switch_work_handler(struct work_struct *work)
{
struct push_switch *psw = container_of(work, struct push_switch, work);
struct platform_device *pdev = psw->pdev;
psw->state = 0;
kobject_uevent(&pdev->dev.kobj, KOBJ_CHANGE);
}
static int switch_drv_probe(struct platform_device *pdev)
{
struct push_switch_platform_info *psw_info;
struct push_switch *psw;
int ret, irq;
psw = kzalloc(sizeof(struct push_switch), GFP_KERNEL);
if (unlikely(!psw))
return -ENOMEM;
irq = platform_get_irq(pdev, 0);
if (unlikely(irq < 0)) {
ret = -ENODEV;
goto err;
}
psw_info = pdev->dev.platform_data;
BUG_ON(!psw_info);
ret = request_irq(irq, psw_info->irq_handler,
psw_info->irq_flags,
psw_info->name ? psw_info->name : DRV_NAME, pdev);
if (unlikely(ret < 0))
goto err;
if (psw_info->name) {
ret = device_create_file(&pdev->dev, &dev_attr_switch);
if (unlikely(ret)) {
dev_err(&pdev->dev, "Failed creating device attrs\n");
ret = -EINVAL;
goto err_irq;
}
}
INIT_WORK(&psw->work, switch_work_handler);
timer_setup(&psw->debounce, switch_timer, 0);
/* Workqueue API brain-damage */
psw->pdev = pdev;
platform_set_drvdata(pdev, psw);
return 0;
err_irq:
free_irq(irq, pdev);
err:
kfree(psw);
return ret;
}
static int switch_drv_remove(struct platform_device *pdev)
{
struct push_switch *psw = platform_get_drvdata(pdev);
struct push_switch_platform_info *psw_info = pdev->dev.platform_data;
int irq = platform_get_irq(pdev, 0);
if (psw_info->name)
device_remove_file(&pdev->dev, &dev_attr_switch);
platform_set_drvdata(pdev, NULL);
timer_shutdown_sync(&psw->debounce);
flush_work(&psw->work);
free_irq(irq, pdev);
kfree(psw);
return 0;
}
static struct platform_driver switch_driver = {
.probe = switch_drv_probe,
.remove = switch_drv_remove,
.driver = {
.name = DRV_NAME,
},
};
static int __init switch_init(void)
{
printk(KERN_NOTICE DRV_NAME ": version %s loaded\n", DRV_VERSION);
return platform_driver_register(&switch_driver);
}
static void __exit switch_exit(void)
{
platform_driver_unregister(&switch_driver);
}
module_init(switch_init);
module_exit(switch_exit);
MODULE_VERSION(DRV_VERSION);
MODULE_AUTHOR("Paul Mundt");
MODULE_LICENSE("GPL v2");