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authorOliver Neukum <oliver@neukum.org>2009-02-12 13:17:52 +0100
committerJiri Kosina <jkosina@suse.cz>2009-03-30 15:12:52 +0200
commite43bd67d721bccbfe144c0b586b0ab3a2a157968 (patch)
tree89e8209365c30266166f0155cccc8a80d41922ea /drivers/hid
parent6f4303fb2ec68055e793b84887a7ae0f9ea7cc2d (diff)
downloadlinux-e43bd67d721bccbfe144c0b586b0ab3a2a157968.tar.bz2
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/hid')
-rw-r--r--drivers/hid/usbhid/hiddev.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c
index aa214170baf4..93dcb7e29102 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;
}