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From:   Suwan Kim <suwan.kim027@gmail.com>
To:     shuah@kernel.org, valentina.manea.m@gmail.com,
        gregkh@linuxfoundation.org, marmarek@invisiblethingslab.com
Cc:     linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        stable@vger.kernel.org, stern@rowland.harvard.edu,
        Suwan Kim <suwan.kim027@gmail.com>
Subject: [PATCH v2 2/2] usbip: Fix error path of vhci_recv_ret_submit()
Date:   Fri, 13 Dec 2019 11:30:55 +0900
Message-Id: <20191213023055.19933-3-suwan.kim027@gmail.com>
In-Reply-To: <20191213023055.19933-1-suwan.kim027@gmail.com>
References: <20191213023055.19933-1-suwan.kim027@gmail.com>
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Sender: linux-kernel-owner@vger.kernel.org
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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);
 
-- 
2.20.1