HID: hiddev cleanup -- handle all error conditions properly

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>

diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c
index 83e851a..6a98f9f 100644 (file)
--- 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);