USB HID: hiddev - fix race between hiddev_send_event() and hiddev_release()
There is a small race window in which hiddev_release() could corrupt the
list that is being processed for new event in hiddev_send_event().
Synchronize the operations over this list.
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c
index a8b3d66..488d61b 100644
--- a/drivers/hid/usbhid/hiddev.c
+++ b/drivers/hid/usbhid/hiddev.c
@@ -51,6 +51,7 @@
wait_queue_head_t wait;
struct hid_device *hid;
struct list_head list;
+ spinlock_t list_lock;
};
struct hiddev_list {
@@ -161,7 +162,9 @@
{
struct hiddev *hiddev = hid->hiddev;
struct hiddev_list *list;
+ unsigned long flags;
+ spin_lock_irqsave(&hiddev->list_lock, flags);
list_for_each_entry(list, &hiddev->list, node) {
if (uref->field_index != HID_FIELD_INDEX_NONE ||
(list->flags & HIDDEV_FLAG_REPORT) != 0) {
@@ -171,6 +174,7 @@
kill_fasync(&list->fasync, SIGIO, POLL_IN);
}
}
+ spin_unlock_irqrestore(&hiddev->list_lock, flags);
wake_up_interruptible(&hiddev->wait);
}
@@ -235,9 +239,13 @@
static int hiddev_release(struct inode * inode, struct file * file)
{
struct hiddev_list *list = file->private_data;
+ unsigned long flags;
hiddev_fasync(-1, file, 0);
+
+ spin_lock_irqsave(&list->hiddev->list_lock, flags);
list_del(&list->node);
+ spin_unlock_irqrestore(&list->hiddev->list_lock, flags);
if (!--list->hiddev->open) {
if (list->hiddev->exist)
@@ -257,6 +265,7 @@
static int hiddev_open(struct inode *inode, struct file *file)
{
struct hiddev_list *list;
+ unsigned long flags;
int i = iminor(inode) - HIDDEV_MINOR_BASE;
@@ -267,7 +276,11 @@
return -ENOMEM;
list->hiddev = hiddev_table[i];
+
+ spin_lock_irqsave(&list->hiddev->list_lock, flags);
list_add_tail(&list->node, &hiddev_table[i]->list);
+ spin_unlock_irqrestore(&list->hiddev->list_lock, flags);
+
file->private_data = list;
if (!list->hiddev->open++)
@@ -773,6 +786,7 @@
init_waitqueue_head(&hiddev->wait);
INIT_LIST_HEAD(&hiddev->list);
+ spin_lock_init(&hiddev->list_lock);
hiddev->hid = hid;
hiddev->exist = 1;