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); }