On 8/13/21 12:25 PM, Anirudh Rayabharam wrote:
In vhci_device_unlink_cleanup(), the URBs for unsent unlink requests are
not given back. This sometimes causes usb_kill_urb to wait indefinitely
for that urb to be given back. syzbot has reported a hung task issue [1]
for this.
To fix this, give back the urbs corresponding to unsent unlink requests
(unlink_tx list) similar to how urbs corresponding to unanswered unlink
requests (unlink_rx list) are given back.
[1]: https://syzkaller.appspot.com/bug?id=08f12df95ae7da69814e64eb5515d5a85ed06b76
Reported-by: syzbot+74d6ef051d3d2eacf428@xxxxxxxxxxxxxxxxxxxxxxxxx
Tested-by: syzbot+74d6ef051d3d2eacf428@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Anirudh Rayabharam <mail@xxxxxxxxxxxxx>
---
drivers/usb/usbip/vhci_hcd.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c
index 4ba6bcdaa8e9..6f3f374d4bbc 100644
--- a/drivers/usb/usbip/vhci_hcd.c
+++ b/drivers/usb/usbip/vhci_hcd.c
@@ -957,8 +957,34 @@ static void vhci_device_unlink_cleanup(struct vhci_device *vdev)
spin_lock(&vdev->priv_lock);
list_for_each_entry_safe(unlink, tmp, &vdev->unlink_tx, list) {
+ struct urb *urb;
+
+ /* give back URB of unsent unlink request */
pr_info("unlink cleanup tx %lu\n", unlink->unlink_seqnum);
I know this is an exiting one.
Let's make this pr_debug or remove it all together.
+
+ urb = pickup_urb_and_free_priv(vdev, unlink->unlink_seqnum);
+ if (!urb) {
+ pr_info("the urb (seqnum %lu) was already given back\n",
+ unlink->unlink_seqnum);
Let's make this pr_debug or remove it all together.
+ list_del(&unlink->list);
+ kfree(unlink);
+ continue;
+ }
+
+ urb->status = -ENODEV;
+
+ usb_hcd_unlink_urb_from_ep(hcd, urb);
+
list_del(&unlink->list);
+
+ spin_unlock(&vdev->priv_lock);
+ spin_unlock_irqrestore(&vhci->lock, flags);
+
+ usb_hcd_giveback_urb(hcd, urb, urb->status);
+
+ spin_lock_irqsave(&vhci->lock, flags);
+ spin_lock(&vdev->priv_lock);
+
kfree(unlink);
}
thanks,
-- Shuah
