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    Subject[PATCH AUTOSEL 4.9 43/48] usbip: give back URBs for unsent unlink requests during cleanup
    Date
    From: Anirudh Rayabharam <mail@anirudhrb.com>

    [ 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@syzkaller.appspotmail.com
    Tested-by: syzbot+74d6ef051d3d2eacf428@syzkaller.appspotmail.com
    Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
    Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com>
    Link: https://lore.kernel.org/r/20210820190122.16379-2-mail@anirudhrb.com
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/usb/usbip/vhci_hcd.c | 24 ++++++++++++++++++++++++
    1 file changed, 24 insertions(+)

    diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c
    index fb7b03029b8e..91ccf57759ae 100644
    --- a/drivers/usb/usbip/vhci_hcd.c
    +++ b/drivers/usb/usbip/vhci_hcd.c
    @@ -762,8 +762,32 @@ 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);
    }

    --
    2.30.2
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