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Commit 277fe44d authored by Yonghua Zheng's avatar Yonghua Zheng Committed by Jiri Kosina
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HID: hidraw: Add spinlock in struct hidraw to protect list 



It is unsafe to call list_for_each_entry in hidraw_report_event to
traverse each hidraw_list node without a lock protection, the list
could be modified if someone calls hidraw_release and list_del to
remove itself from the list, this can cause hidraw_report_event
to touch a deleted list struct and panic.

To prevent this, introduce a spinlock in struct hidraw to protect
list from concurrent access.

Signed-off-by: default avatarYonghua Zheng <younghua.zheng@gmail.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 06bb5219

drivers/hid/hidraw.c

+15 −5
Original line number Diff line number Diff line
@@ -253,6 +253,7 @@ static int hidraw_open(struct inode *inode, struct file *file) 
	unsigned int minor = iminor(inode);

	struct hidraw *dev;

	struct hidraw_list *list;

	unsigned long flags;

	int err = 0;



	if (!(list = kzalloc(sizeof(struct hidraw_list), GFP_KERNEL))) {
@@ -266,11 +267,6 @@ static int hidraw_open(struct inode *inode, struct file *file) 
		goto out_unlock;

	}



	list->hidraw = hidraw_table[minor];

	mutex_init(&list->read_mutex);

	list_add_tail(&list->node, &hidraw_table[minor]->list);

	file->private_data = list;



	dev = hidraw_table[minor];

	if (!dev->open++) {

		err = hid_hw_power(dev->hid, PM_HINT_FULLON);
@@ -283,9 +279,16 @@ static int hidraw_open(struct inode *inode, struct file *file) 
		if (err < 0) {

			hid_hw_power(dev->hid, PM_HINT_NORMAL);

			dev->open--;

			goto out_unlock;

		}

	}



	list->hidraw = hidraw_table[minor];

	mutex_init(&list->read_mutex);

	spin_lock_irqsave(&hidraw_table[minor]->list_lock, flags);

	list_add_tail(&list->node, &hidraw_table[minor]->list);

	spin_unlock_irqrestore(&hidraw_table[minor]->list_lock, flags);

	file->private_data = list;

out_unlock:

	mutex_unlock(&minors_lock);

out:
@@ -324,10 +327,13 @@ static int hidraw_release(struct inode * inode, struct file * file) 
{

	unsigned int minor = iminor(inode);

	struct hidraw_list *list = file->private_data;

	unsigned long flags;



	mutex_lock(&minors_lock);



	spin_lock_irqsave(&hidraw_table[minor]->list_lock, flags);

	list_del(&list->node);

	spin_unlock_irqrestore(&hidraw_table[minor]->list_lock, flags);

	kfree(list);



	drop_ref(hidraw_table[minor], 0);
@@ -456,7 +462,9 @@ int hidraw_report_event(struct hid_device *hid, u8 *data, int len) 
	struct hidraw *dev = hid->hidraw;

	struct hidraw_list *list;

	int ret = 0;

	unsigned long flags;



	spin_lock_irqsave(&dev->list_lock, flags);

	list_for_each_entry(list, &dev->list, node) {

		int new_head = (list->head + 1) & (HIDRAW_BUFFER_SIZE - 1);
@@ -471,6 +479,7 @@ int hidraw_report_event(struct hid_device *hid, u8 *data, int len) 
		list->head = new_head;

		kill_fasync(&list->fasync, SIGIO, POLL_IN);

	}

	spin_unlock_irqrestore(&dev->list_lock, flags);



	wake_up_interruptible(&dev->wait);

	return ret;
@@ -519,6 +528,7 @@ int hidraw_connect(struct hid_device *hid) 


	mutex_unlock(&minors_lock);

	init_waitqueue_head(&dev->wait);

	spin_lock_init(&dev->list_lock);

	INIT_LIST_HEAD(&dev->list);



	dev->hid = hid;

include/linux/hidraw.h

+1 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ struct hidraw { 
	wait_queue_head_t wait;

	struct hid_device *hid;

	struct device *dev;

	spinlock_t list_lock;

	struct list_head list;

};