This is a cleanup of hiddev and fixes the following issues:
- thread safety by locking in read & ioctl, introducing a per device mutex
- race between ioctl and disconnect, introducing a flag and locking
in form of a per low level device mutex
- race between open and other methods, making sure only successfully
opened devices are put on the list, changing order of events
- range checking both upper and lower limits of the minor range
- make sure further calls to open fail for unplugged devices even if
the device still has opened files
- error checking for low level open
- possible loss of wakeup events, using standard waiting macros
- race in initialisation by moving registration after full initialisation
Signed-off-by: Oliver Neukum <oneukum@xxxxxxx>
Regards
Oliver
----
diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c
index 83e851a..defe912 100644
--- a/drivers/hid/usbhid/hiddev.c
+++ b/drivers/hid/usbhid/hiddev.c
@@ -49,6 +49,7 @@
struct hiddev {
int exist;
int open;
+ struct mutex existancelock;
wait_queue_head_t wait;
struct hid_device *hid;
struct list_head list;
@@ -63,6 +64,7 @@ struct hiddev_list {
struct fasync_struct *fasync;
struct hiddev *hiddev;
struct list_head node;
+ struct mutex thread_lock;
};
static struct hiddev *hiddev_table[HIDDEV_MINORS];
@@ -264,29 +266,48 @@ static int hiddev_release(struct inode * inode, struct file * file)
static int hiddev_open(struct inode *inode, struct file *file)
{
struct hiddev_list *list;
- unsigned long flags;
+ int res;
int i = iminor(inode) - HIDDEV_MINOR_BASE;
- if (i >= HIDDEV_MINORS || !hiddev_table[i])
+ if (i >= HIDDEV_MINORS || i < 0 || !hiddev_table[i])
return -ENODEV;
if (!(list = kzalloc(sizeof(struct hiddev_list), GFP_KERNEL)))
return -ENOMEM;
+ mutex_init(&list->thread_lock);
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++)
- if (list->hiddev->exist)
- usbhid_open(hiddev_table[i]->hid);
+ /*
+ * no need for locking because the USB major number
+ * is shared which usbcore guards against disconnect
+ */
+ if (list->hiddev->exist) {
+ if (!list->hiddev->open++) {
+ res = usbhid_open(hiddev_table[i]->hid);
+ if (res < 0) {
+ res = -EIO;
+ goto bail;
+ }
+ }
+ } else {
+ res = -ENODEV;
+ goto bail;
+ }
+
+ spin_lock_irq(&list->hiddev->list_lock);
+ list_add_tail(&list->node, &hiddev_table[i]->list);
+ spin_unlock_irq(&list->hiddev->list_lock);
return 0;
+bail:
+ file->private_data = NULL;
+ kfree(list->hiddev);
+ return res;
}
/*
@@ -305,7 +326,7 @@ static ssize_t hiddev_read(struct file * file, char __user * buffer, size_t coun
DECLARE_WAITQUEUE(wait, current);
struct hiddev_list *list = file->private_data;
int event_size;
- int retval = 0;
+ int retval;
event_size = ((list->flags & HIDDEV_FLAG_UREF) != 0) ?
sizeof(struct hiddev_usage_ref) : sizeof(struct hiddev_event);
@@ -313,10 +334,14 @@ static ssize_t hiddev_read(struct file * file, char __user * buffer, size_t coun
if (count < event_size)
return 0;
+ /* lock against other threads */
+ retval = mutex_lock_interruptible(&list->thread_lock);
+ if (retval)
+ return -ERESTARTSYS;
+
while (retval == 0) {
if (list->head == list->tail) {
- add_wait_queue(&list->hiddev->wait, &wait);
- set_current_state(TASK_INTERRUPTIBLE);
+ prepare_to_wait(&list->hiddev->wait, &wait, TASK_INTERRUPTIBLE);
while (list->head == list->tail) {
if (file->f_flags & O_NONBLOCK) {
@@ -332,35 +357,45 @@ static ssize_t hiddev_read(struct file * file, char __user * buffer, size_t coun
break;
}
+ /* let O_NONBLOCK tasks run */
+ mutex_unlock(&list->thread_lock);
schedule();
+ if (mutex_lock_interruptible(&list->thread_lock))
+ return -EINTR;
set_current_state(TASK_INTERRUPTIBLE);
}
+ finish_wait(&list->hiddev->wait, &wait);
- set_current_state(TASK_RUNNING);
- remove_wait_queue(&list->hiddev->wait, &wait);
}
- if (retval)
+ if (retval) {
+ mutex_unlock(&list->thread_lock);
return retval;
+ }
while (list->head != list->tail &&
retval + event_size <= count) {
if ((list->flags & HIDDEV_FLAG_UREF) == 0) {
- if (list->buffer[list->tail].field_index !=
- HID_FIELD_INDEX_NONE) {
+ if (list->buffer[list->tail].field_index != HID_FIELD_INDEX_NONE) {
struct hiddev_event event;
+
event.hid = list->buffer[list->tail].usage_code;
event.value = list->buffer[list->tail].value;
- if (copy_to_user(buffer + retval, &event, sizeof(struct hiddev_event)))
+ if (copy_to_user(buffer + retval, &event, sizeof(struct hiddev_event))) {
+ mutex_unlock(&list->thread_lock);
return -EFAULT;
+ }
retval += sizeof(struct hiddev_event);
}
} else {
if (list->buffer[list->tail].field_index != HID_FIELD_INDEX_NONE ||
(list->flags & HIDDEV_FLAG_REPORT) != 0) {
- if (copy_to_user(buffer + retval, list->buffer + list->tail, sizeof(struct hiddev_usage_ref)))
+
+ if (copy_to_user(buffer + retval, list->buffer + list->tail, sizeof(struct hiddev_usage_ref))) {
+ mutex_unlock(&list->thread_lock);
return -EFAULT;
+ }
retval += sizeof(struct hiddev_usage_ref);
}
}
@@ -368,6 +403,7 @@ static ssize_t hiddev_read(struct file * file, char __user * buffer, size_t coun
}
}
+ mutex_unlock(&list->thread_lock);
return retval;
}
@@ -555,7 +591,7 @@ static long hiddev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
struct hid_field *field;
struct usbhid_device *usbhid = hid->driver_data;
void __user *user_arg = (void __user *)arg;
- int i;
+ int i, r;
/* Called without BKL by compat methods so no BKL taken */
@@ -619,10 +655,22 @@ static long hiddev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
}
case HIDIOCGSTRING:
- return hiddev_ioctl_string(hiddev, cmd, user_arg);
+ mutex_lock(&hiddev->existancelock);
+ if (!hiddev->exist)
+ r = hiddev_ioctl_string(hiddev, cmd, user_arg);
+ else
+ r = -ENODEV;
+ mutex_unlock(&hiddev->existancelock);
+ return r;
case HIDIOCINITREPORT:
+ mutex_lock(&hiddev->existancelock);
+ if (!hiddev->exist) {
+ mutex_unlock(&hiddev->existancelock);
+ return -ENODEV;
+ }
usbhid_init_reports(hid);
+ mutex_unlock(&hiddev->existancelock);
return 0;
@@ -636,8 +684,12 @@ static long hiddev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
if ((report = hiddev_lookup_report(hid, &rinfo)) == NULL)
return -EINVAL;
- usbhid_submit_report(hid, report, USB_DIR_IN);
- usbhid_wait_io(hid);
+ mutex_lock(&hiddev->existancelock);
+ if (hiddev->exist) {
+ usbhid_submit_report(hid, report, USB_DIR_IN);
+ usbhid_wait_io(hid);
+ }
+ mutex_unlock(&hiddev->existancelock);
return 0;
@@ -651,8 +703,12 @@ static long hiddev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
if ((report = hiddev_lookup_report(hid, &rinfo)) == NULL)
return -EINVAL;
- usbhid_submit_report(hid, report, USB_DIR_OUT);
- usbhid_wait_io(hid);
+ mutex_lock(&hiddev->existancelock);
+ if (hiddev->exist) {
+ usbhid_submit_report(hid, report, USB_DIR_OUT);
+ usbhid_wait_io(hid);
+ }
+ mutex_unlock(&hiddev->existancelock);
return 0;
@@ -710,7 +766,13 @@ static long hiddev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
case HIDIOCGUSAGES:
case HIDIOCSUSAGES:
case HIDIOCGCOLLECTIONINDEX:
- return hiddev_ioctl_usage(hiddev, cmd, user_arg);
+ mutex_lock(&hiddev->existancelock);
+ if (hiddev->exist)
+ r = hiddev_ioctl_usage(hiddev, cmd, user_arg);
+ else
+ r = -ENODEV;
+ mutex_unlock(&hiddev->existancelock);
+ return r;
case HIDIOCGCOLLECTIONINFO:
if (copy_from_user(&cinfo, user_arg, sizeof(cinfo)))
@@ -808,23 +870,22 @@ int hiddev_connect(struct hid_device *hid, unsigned int force)
if (!(hiddev = kzalloc(sizeof(struct hiddev), GFP_KERNEL)))
return -1;
- retval = usb_register_dev(usbhid->intf, &hiddev_class);
- if (retval) {
- err_hid("Not able to get a minor for this device.");
- kfree(hiddev);
- return -1;
- }
-
init_waitqueue_head(&hiddev->wait);
INIT_LIST_HEAD(&hiddev->list);
spin_lock_init(&hiddev->list_lock);
+ mutex_init(&hiddev->existancelock);
hiddev->hid = hid;
hiddev->exist = 1;
- hid->minor = usbhid->intf->minor;
- hid->hiddev = hiddev;
-
- hiddev_table[usbhid->intf->minor - HIDDEV_MINOR_BASE] = hiddev;
+ retval = usb_register_dev(usbhid->intf, &hiddev_class);
+ if (retval) {
+ err_hid("Not able to get a minor for this device.");
+ kfree(hiddev);
+ return -1;
+ } else {
+ hid->minor = usbhid->intf->minor;
+ hiddev_table[usbhid->intf->minor - HIDDEV_MINOR_BASE] = hiddev;
+ }
return 0;
}
@@ -839,7 +900,9 @@ void hiddev_disconnect(struct hid_device *hid)
struct hiddev *hiddev = hid->hiddev;
struct usbhid_device *usbhid = hid->driver_data;
+ mutex_lock(&hiddev->existancelock);
hiddev->exist = 0;
+ mutex_unlock(&hiddev->existancelock);
hiddev_table[hiddev->hid->minor - HIDDEV_MINOR_BASE] = NULL;
usb_deregister_dev(usbhid->intf, &hiddev_class);
--
To unsubscribe from this list: send the line "unsubscribe linux-input" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
