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authorYonghua Zheng <younghua.zheng@gmail.com>2013-08-26 23:38:35 +0800
committerJiri Kosina <jkosina@suse.cz>2013-08-26 21:40:24 +0200
commit277fe44dd862412ee034470ad1c13a79d24e533b (patch)
tree7333fed46331fc756cfde7dfd58a1127de97955b
parent06bb5219118fb098f4b0c7dcb484b28a52bf1c14 (diff)
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>
-rw-r--r--drivers/hid/hidraw.c20
-rw-r--r--include/linux/hidraw.h1
2 files changed, 16 insertions, 5 deletions
diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index 612a655bc9f0..194a5660a389 100644
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -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;
diff --git a/include/linux/hidraw.h b/include/linux/hidraw.h
index 2451662c728a..ddf52612eed8 100644
--- a/include/linux/hidraw.h
+++ b/include/linux/hidraw.h
@@ -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;
};