diff options
| author | Oliver Neukum <oliver@neukum.org> | 2009-02-12 13:17:52 +0100 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2009-03-30 15:12:52 +0200 |
| commit | e43bd67d721bccbfe144c0b586b0ab3a2a157968 (patch) | |
| tree | 89e8209365c30266166f0155cccc8a80d41922ea /drivers | |
| parent | 6f4303fb2ec68055e793b84887a7ae0f9ea7cc2d (diff) | |
HID: fix race between usb_register_dev() and hiddev_open()
upon further thought this code is still racy.
retval = usb_register_dev(usbhid->intf, &hiddev_class);
here you open a window during which open can happen
if (retval) {
err_hid("Not able to get a minor for this device.");
hid->hiddev = NULL;
kfree(hiddev);
return -1;
} else {
hid->minor = usbhid->intf->minor;
hiddev_table[usbhid->intf->minor - HIDDEV_MINOR_BASE] = hiddev;
and will fail because hiddev_table hasn't been updated
The obvious fix of using a mutex to guard hiddev_table doesn't work because
usb_open() and usb_register_dev() take minor_rwsem and we'd have an AB-BA
deadlock. We need a lock usb_open() also takes in the right order and that leaves
only one option, BKL. I don't like it but I see no alternative.
Once the usb_open() implements something better than lock_kernel(), we could also
do so.
Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/hid/usbhid/hiddev.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c index aa214170baf..93dcb7e2910 100644 --- a/drivers/hid/usbhid/hiddev.c +++ b/drivers/hid/usbhid/hiddev.c @@ -875,16 +875,21 @@ int hiddev_connect(struct hid_device *hid, unsigned int force) hiddev->hid = hid; hiddev->exist = 1; + /* when lock_kernel() usage is fixed in usb_open(), + * we could also fix it here */ + lock_kernel(); retval = usb_register_dev(usbhid->intf, &hiddev_class); if (retval) { err_hid("Not able to get a minor for this device."); hid->hiddev = NULL; + unlock_kernel(); kfree(hiddev); return -1; } else { hid->minor = usbhid->intf->minor; hiddev_table[usbhid->intf->minor - HIDDEV_MINOR_BASE] = hiddev; } + unlock_kernel(); return 0; } |