Re: [PATCH v2 2/2] usbip: Fix error path of vhci_recv_ret_submit()

[shuah <shuah@kernel.org>]

On 12/12/19 7:30 PM, Suwan Kim wrote:
> If a transaction error happens in vhci_recv_ret_submit(), event
> handler closes connection and changes port status to kick hub_event.
> Then hub tries to flush the endpoint URBs, but that causes infinite
> loop between usb_hub_flush_endpoint() and vhci_urb_dequeue() because
> "vhci_priv" in vhci_urb_dequeue() was already released by
> vhci_recv_ret_submit() before a transmission error occurred. Thus,
> vhci_urb_dequeue() terminates early and usb_hub_flush_endpoint()
> continuously calls vhci_urb_dequeue().
> 
> The root cause of this issue is that vhci_recv_ret_submit()
> terminates early without giving back URB when transaction error
> occurs in vhci_recv_ret_submit(). That causes the error URB to still
> be linked at endpoint list without “vhci_priv".
> 
> So, in the case of transaction error in vhci_recv_ret_submit(),
> unlink URB from the endpoint, insert proper error code in
> urb->status and give back URB.
> 
> Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
> Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
> Signed-off-by: Suwan Kim <suwan.kim027@gmail.com>
> ---
>   drivers/usb/usbip/vhci_rx.c | 13 +++++++++----
>   1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/usbip/vhci_rx.c b/drivers/usb/usbip/vhci_rx.c
> index 33f8972ba842..00fc98741c5d 100644
> --- a/drivers/usb/usbip/vhci_rx.c
> +++ b/drivers/usb/usbip/vhci_rx.c
> @@ -77,16 +77,21 @@ static void vhci_recv_ret_submit(struct vhci_device *vdev,
>   	usbip_pack_pdu(pdu, urb, USBIP_RET_SUBMIT, 0);
>   
>   	/* recv transfer buffer */
> -	if (usbip_recv_xbuff(ud, urb) < 0)
> -		return;
> +	if (usbip_recv_xbuff(ud, urb) < 0) {
> +		urb->status = -EPROTO;
> +		goto error;
> +	}
>   
>   	/* recv iso_packet_descriptor */
> -	if (usbip_recv_iso(ud, urb) < 0)
> -		return;
> +	if (usbip_recv_iso(ud, urb) < 0) {
> +		urb->status = -EPROTO;
> +		goto error;
> +	}
>   
>   	/* restore the padding in iso packets */
>   	usbip_pad_iso(ud, urb);
>   
> +error:
>   	if (usbip_dbg_flag_vhci_rx)
>   		usbip_dump_urb(urb);
>   
> 

Acked-by: Shuah Khan <skhan@linuxfoundation.org>

thanks,
-- Shuah