If cfgdata length exceeds the command buffer size we will end up
getting buffer overflow problem. Fix it by checking the buffer
size less the command header length.
Reviewed-by: Paul Stewart <pstew@chromium.org>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>