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Subject[patch 63/69] USB HID: hiddev - fix race between hiddev_send_event() and hiddev_release()
-stable review patch.  If anyone has any objections, please let us know.
---------------------

From: Jiri Kosina <jkosina@suse.cz>

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>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
(in Linus' tree as cdcb44e87bedcf5070eece61f89f9373a3810031)

---
drivers/usb/input/hiddev.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

--- linux-2.6.21.1.orig/drivers/usb/input/hiddev.c
+++ linux-2.6.21.1/drivers/usb/input/hiddev.c
@@ -51,6 +51,7 @@ struct hiddev {
wait_queue_head_t wait;
struct hid_device *hid;
struct list_head list;
+ spinlock_t list_lock;
};

struct hiddev_list {
@@ -161,7 +162,9 @@ static void hiddev_send_event(struct hid
{
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 @@ static void hiddev_send_event(struct hid
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_fasync(int fd, struct
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_release(struct inode *
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 @@ static int hiddev_open(struct inode *ino
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 @@ int hiddev_connect(struct hid_device *hi

init_waitqueue_head(&hiddev->wait);
INIT_LIST_HEAD(&hiddev->list);
+ spin_lock_init(&hiddev->list_lock);
hiddev->hid = hid;
hiddev->exist = 1;

--
-
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