Patch "usbip: give back URBs for unsent unlink requests during cleanup" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    usbip: give back URBs for unsent unlink requests during cleanup

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usbip-give-back-urbs-for-unsent-unlink-requests-duri.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit b15b02a0a0f4684b8a4068492b8c71ea4d7a300d
Author: Anirudh Rayabharam <mail@xxxxxxxxxxxxx>
Date:   Sat Aug 21 00:31:21 2021 +0530

    usbip: give back URBs for unsent unlink requests during cleanup
    
    [ Upstream commit 258c81b341c8025d79073ce2d6ce19dcdc7d10d2 ]
    
    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
    Reviewed-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Anirudh Rayabharam <mail@xxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20210820190122.16379-2-mail@xxxxxxxxxxxxx
    Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c
index b13ed5a7618d..a4ead4099869 100644
--- a/drivers/usb/usbip/vhci_hcd.c
+++ b/drivers/usb/usbip/vhci_hcd.c
@@ -957,8 +957,32 @@ 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);
+
+		urb = pickup_urb_and_free_priv(vdev, unlink->unlink_seqnum);
+		if (!urb) {
+			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);
 	}