usb: misc: usbtest: fix error of urb allocation

urb allocation will fail when usbtest_alloc_urb() tries to
allocate zero length buffer, but it doesn't need it in fact,
so just skips buffer allocation in the case.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/usb/misc/usbtest.c b/drivers/usb/misc/usbtest.c
index 92fdb6e9faff..de485d8a5beb 100644
--- a/drivers/usb/misc/usbtest.c
+++ b/drivers/usb/misc/usbtest.c
@@ -287,6 +287,9 @@ static struct urb *usbtest_alloc_urb(
         if (usb_pipein(pipe))
                 urb->transfer_flags |= URB_SHORT_NOT_OK;
 
+        if ((bytes + offset) == 0)
+                return urb;
+
         if (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)
                 urb->transfer_buffer = usb_alloc_coherent(udev, bytes + offset,
                         GFP_KERNEL, &urb->transfer_dma);