HID: hiddev: fix race between hiddev_disconnect and hiddev_release
When hiddev_disconnect() runs with chardev open, it will proceed with
usbhid_close(). When userspace in parallel runs the hiddev_release(),
it sees !hiddev->exists (as it has been already set so by
hiddev_disconnect()) and kfrees hiddev while hiddev_disconnect() hasn't
finished yet.
Serialize the access to hiddev->exists and hiddev->open by existancelock.
Reported-by: mike-@cinci.rr.com
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c
index 2baa71e..f4c67a5 100644
--- a/drivers/hid/usbhid/hiddev.c
+++ b/drivers/hid/usbhid/hiddev.c
@@ -242,6 +242,7 @@
list_del(&list->node);
spin_unlock_irqrestore(&list->hiddev->list_lock, flags);
+ mutex_lock(&list->hiddev->existancelock);
if (!--list->hiddev->open) {
if (list->hiddev->exist) {
usbhid_close(list->hiddev->hid);
@@ -252,6 +253,7 @@
}
kfree(list);
+ mutex_unlock(&list->hiddev->existancelock);
return 0;
}
@@ -300,17 +302,21 @@
list_add_tail(&list->node, &hiddev->list);
spin_unlock_irq(&list->hiddev->list_lock);
+ mutex_lock(&hiddev->existancelock);
if (!list->hiddev->open++)
if (list->hiddev->exist) {
struct hid_device *hid = hiddev->hid;
res = usbhid_get_power(hid);
if (res < 0) {
res = -EIO;
- goto bail;
+ goto bail_unlock;
}
usbhid_open(hid);
}
+ mutex_unlock(&hiddev->existancelock);
return 0;
+bail_unlock:
+ mutex_unlock(&hiddev->existancelock);
bail:
file->private_data = NULL;
kfree(list);
@@ -911,7 +917,6 @@
mutex_lock(&hiddev->existancelock);
hiddev->exist = 0;
- mutex_unlock(&hiddev->existancelock);
usb_deregister_dev(usbhid->intf, &hiddev_class);
@@ -921,4 +926,5 @@
} else {
kfree(hiddev);
}
+ mutex_unlock(&hiddev->existancelock);
}