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HID: hiddev cleanup -- handle all error conditions properly
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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@suse.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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Oliver Neukum authored and Jiri Kosina committed Jan 4, 2009
1 parent 42859e0 commit 0790340
Showing 1 changed file with 99 additions and 36 deletions.
135 changes: 99 additions & 36 deletions drivers/hid/usbhid/hiddev.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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];
Expand Down Expand Up @@ -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;
}

/*
Expand All @@ -305,18 +326,22 @@ 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);

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) {
Expand All @@ -332,42 +357,53 @@ 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);
}
}
list->tail = (list->tail + 1) & (HIDDEV_BUFFER_SIZE - 1);
}

}
mutex_unlock(&list->thread_lock);

return retval;
}
Expand Down Expand Up @@ -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 */

Expand Down Expand Up @@ -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;

Expand All @@ -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;

Expand All @@ -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;

Expand Down Expand Up @@ -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)))
Expand Down Expand Up @@ -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;
}
Expand All @@ -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);
Expand Down

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