usbip: Fix receive error in vhci-hcd when using scatter-gather

BugLink: https://bugs.launchpad.net/bugs/1859712
commit d986294ee55d719562b20aabe15a39bf8f863415 upstream.

When vhci uses SG and receives data whose size is smaller than SG
buffer size, it tries to receive more data even if it acutally
receives all the data from the server. If then, it erroneously adds
error event and triggers connection shutdown.

vhci-hcd should check if it received all the data even if there are
more SG entries left. So, check if it receivces all the data from
the server in for_each_sg() loop.

Fixes: ea44d190764b ("usbip: Implement SG support to vhci-hcd and stub driver")
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>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191213023055.19933-2-suwan.kim027@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/usb/usbip/usbip_common.c b/drivers/usb/usbip/usbip_common.c
index ece5a59fb5325ba8d22e5d3387e1e90c04357f25..2879e7ab5337a75f7b7d4e6cc025e5d7010c0287 100644 (file)
--- a/drivers/usb/usbip/usbip_common.c
+++ b/drivers/usb/usbip/usbip_common.c
@@ -728,6 +728,9 @@ int usbip_recv_xbuff(struct usbip_device *ud, struct urb *urb)
 
                        copy -= recv;
                        ret += recv;
+
+                       if (!copy)
+                               break;
                }
 
                if (ret != size)