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Subject[PATCH 2/2] usbip: Fix error path of vhci_recv_ret_submit()
Date
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(),
unlink URB from the endpoint, insert proper error code in
urb->status and give back URB.

Reported-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..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);

--
2.20.1
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