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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: Yonghua Zheng <younghua.zheng@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This commit is contained in:
Yonghua Zheng 2013-08-26 23:38:35 +08:00 committed by Jiri Kosina
parent 06bb521911
commit 277fe44dd8
2 changed files with 16 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
drivers/hid/hidraw.c
View File

@ -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;

1
include/linux/hidraw.h
View File

@ -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;
};