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4a2a8a2cce
The usbfs code doesn't provide sufficient mutual exclusion among open, release, and remove. Release vs. remove is okay because they both acquire the device lock, but open is not exclusive with either one. All three routines modify the udev->filelist linked list, so they must not run concurrently. Apparently someone gave this a minimum amount of thought in the past by explicitly acquiring the BKL at the start of the usbdev_open routine. Oddly enough, there's a comment pointing out that locking is unnecessary because chrdev_open already has acquired the BKL. But this ignores the point that the files in /proc/bus/usb/* are not char device files; they are regular files and so they don't get any special locking. Furthermore it's necessary to acquire the same lock in the release and remove routines, which the code does not do. Yet another problem arises because the same file_operations structure is accessible through both the /proc/bus/usb/* and /dev/usb/usbdev* file nodes. Even when one of them has been removed, it's still possible for userspace to open the other. So simple locking around the individual remove routines is insufficient; we need to lock the entire usb_notify_remove_device notifier chain. Rather than rely on the BKL, this patch (as723) introduces a new private mutex for the purpose. Holding the BKL while invoking a notifier chain doesn't seem like a good idea. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
93 lines
3.1 KiB
C
93 lines
3.1 KiB
C
/* Functions local to drivers/usb/core/ */
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extern void usb_create_sysfs_dev_files (struct usb_device *dev);
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extern void usb_remove_sysfs_dev_files (struct usb_device *dev);
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extern void usb_create_sysfs_intf_files (struct usb_interface *intf);
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extern void usb_remove_sysfs_intf_files (struct usb_interface *intf);
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extern void usb_create_ep_files(struct device *parent, struct usb_host_endpoint *endpoint,
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struct usb_device *udev);
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extern void usb_remove_ep_files(struct usb_host_endpoint *endpoint);
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extern void usb_disable_endpoint (struct usb_device *dev, unsigned int epaddr);
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extern void usb_disable_interface (struct usb_device *dev,
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struct usb_interface *intf);
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extern void usb_release_interface_cache(struct kref *ref);
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extern void usb_disable_device (struct usb_device *dev, int skip_ep0);
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extern int usb_get_device_descriptor(struct usb_device *dev,
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unsigned int size);
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extern char *usb_cache_string(struct usb_device *udev, int index);
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extern int usb_set_configuration(struct usb_device *dev, int configuration);
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extern void usb_kick_khubd(struct usb_device *dev);
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extern void usb_suspend_root_hub(struct usb_device *hdev);
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extern void usb_resume_root_hub(struct usb_device *dev);
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extern int usb_hub_init(void);
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extern void usb_hub_cleanup(void);
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extern int usb_major_init(void);
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extern void usb_major_cleanup(void);
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extern int usb_host_init(void);
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extern void usb_host_cleanup(void);
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extern int usb_suspend_device(struct usb_device *dev);
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extern int usb_resume_device(struct usb_device *dev);
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extern struct device_driver usb_generic_driver;
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extern int usb_generic_driver_data;
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extern int usb_device_match(struct device *dev, struct device_driver *drv);
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/* Interfaces and their "power state" are owned by usbcore */
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static inline void mark_active(struct usb_interface *f)
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{
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f->dev.power.power_state.event = PM_EVENT_ON;
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}
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static inline void mark_quiesced(struct usb_interface *f)
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{
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f->dev.power.power_state.event = PM_EVENT_FREEZE;
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}
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static inline int is_active(struct usb_interface *f)
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{
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return f->dev.power.power_state.event == PM_EVENT_ON;
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}
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/* for labeling diagnostics */
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extern const char *usbcore_name;
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/* usbfs stuff */
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extern struct mutex usbfs_mutex;
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extern struct usb_driver usbfs_driver;
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extern struct file_operations usbfs_devices_fops;
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extern struct file_operations usbfs_device_file_operations;
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extern void usbfs_conn_disc_event(void);
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extern int usbdev_init(void);
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extern void usbdev_cleanup(void);
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struct dev_state {
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struct list_head list; /* state list */
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struct usb_device *dev;
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struct file *file;
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spinlock_t lock; /* protects the async urb lists */
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struct list_head async_pending;
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struct list_head async_completed;
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wait_queue_head_t wait; /* wake up if a request completed */
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unsigned int discsignr;
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pid_t disc_pid;
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uid_t disc_uid, disc_euid;
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void __user *disccontext;
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unsigned long ifclaimed;
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u32 secid;
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};
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/* internal notify stuff */
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extern void usb_notify_add_device(struct usb_device *udev);
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extern void usb_notify_remove_device(struct usb_device *udev);
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extern void usb_notify_add_bus(struct usb_bus *ubus);
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extern void usb_notify_remove_bus(struct usb_bus *ubus);
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