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246f80a0b1
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>
137 lines
2.9 KiB
C
137 lines
2.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Generic push-switch framework
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*
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* Copyright (C) 2006 Paul Mundt
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*/
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/platform_device.h>
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#include <asm/push-switch.h>
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#define DRV_NAME "push-switch"
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#define DRV_VERSION "0.1.1"
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static ssize_t switch_show(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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struct push_switch_platform_info *psw_info = dev->platform_data;
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return sprintf(buf, "%s\n", psw_info->name);
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}
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static DEVICE_ATTR_RO(switch);
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static void switch_timer(struct timer_list *t)
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{
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struct push_switch *psw = from_timer(psw, t, debounce);
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schedule_work(&psw->work);
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}
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static void switch_work_handler(struct work_struct *work)
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{
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struct push_switch *psw = container_of(work, struct push_switch, work);
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struct platform_device *pdev = psw->pdev;
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psw->state = 0;
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kobject_uevent(&pdev->dev.kobj, KOBJ_CHANGE);
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}
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static int switch_drv_probe(struct platform_device *pdev)
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{
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struct push_switch_platform_info *psw_info;
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struct push_switch *psw;
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int ret, irq;
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psw = kzalloc(sizeof(struct push_switch), GFP_KERNEL);
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if (unlikely(!psw))
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return -ENOMEM;
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irq = platform_get_irq(pdev, 0);
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if (unlikely(irq < 0)) {
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ret = -ENODEV;
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goto err;
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}
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psw_info = pdev->dev.platform_data;
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BUG_ON(!psw_info);
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ret = request_irq(irq, psw_info->irq_handler,
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psw_info->irq_flags,
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psw_info->name ? psw_info->name : DRV_NAME, pdev);
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if (unlikely(ret < 0))
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goto err;
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if (psw_info->name) {
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ret = device_create_file(&pdev->dev, &dev_attr_switch);
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if (unlikely(ret)) {
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dev_err(&pdev->dev, "Failed creating device attrs\n");
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ret = -EINVAL;
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goto err_irq;
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}
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}
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INIT_WORK(&psw->work, switch_work_handler);
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timer_setup(&psw->debounce, switch_timer, 0);
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/* Workqueue API brain-damage */
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psw->pdev = pdev;
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platform_set_drvdata(pdev, psw);
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return 0;
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err_irq:
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free_irq(irq, pdev);
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err:
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kfree(psw);
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return ret;
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}
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static int switch_drv_remove(struct platform_device *pdev)
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{
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struct push_switch *psw = platform_get_drvdata(pdev);
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struct push_switch_platform_info *psw_info = pdev->dev.platform_data;
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int irq = platform_get_irq(pdev, 0);
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if (psw_info->name)
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device_remove_file(&pdev->dev, &dev_attr_switch);
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platform_set_drvdata(pdev, NULL);
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timer_shutdown_sync(&psw->debounce);
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flush_work(&psw->work);
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free_irq(irq, pdev);
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kfree(psw);
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return 0;
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}
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static struct platform_driver switch_driver = {
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.probe = switch_drv_probe,
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.remove = switch_drv_remove,
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.driver = {
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.name = DRV_NAME,
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},
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};
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static int __init switch_init(void)
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{
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printk(KERN_NOTICE DRV_NAME ": version %s loaded\n", DRV_VERSION);
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return platform_driver_register(&switch_driver);
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}
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static void __exit switch_exit(void)
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{
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platform_driver_unregister(&switch_driver);
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}
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module_init(switch_init);
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module_exit(switch_exit);
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MODULE_VERSION(DRV_VERSION);
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MODULE_AUTHOR("Paul Mundt");
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MODULE_LICENSE("GPL v2");
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