linux-kernel - Re: [PATCH 2/2] usbip: Fix error path of vhci_recv_ret

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Date:   Thu, 12 Dec 2019 12:45:40 +0100
From:   Marek Marczykowski-Górecki 
        <marmarek@...isiblethingslab.com>
To:     Suwan Kim <suwan.kim027@...il.com>
Cc:     shuah@...nel.org, valentina.manea.m@...il.com,
        gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 2/2] usbip: Fix error path of vhci_recv_ret_submit()

On Thu, Dec 12, 2019 at 02:28:41PM +0900, 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 trasnaction error in vhci_recv_ret_submit(),
                       ^^^ typo

> unlink URB from the endpoint, insert proper error code in
> urb->status and give back URB.
> 
> Reported-by: Marek Marczykowski-Górecki <marmarek@...isiblethingslab.com>
> Signed-off-by: Suwan Kim <suwan.kim027@...il.com>

Tested-by: Marek Marczykowski-Górecki <marmarek@...isiblethingslab.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..dc26acad6baf 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 = -EPIPE;
> +		goto error;
> +	}
>  
>  	/* recv iso_packet_descriptor */
> -	if (usbip_recv_iso(ud, urb) < 0)
> -		return;
> +	if (usbip_recv_iso(ud, urb) < 0) {
> +		urb->status = -EPIPE;
> +		goto error;
> +	}
>  
>  	/* restore the padding in iso packets */
>  	usbip_pad_iso(ud, urb);
>  
> +error:
>  	if (usbip_dbg_flag_vhci_rx)
>  		usbip_dump_urb(urb);
>  

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

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