display-sys: function mode_string check input parameter.

Signed-off-by: Zheng Yang <zhengyang@rock-chips.com>

diff --git a/drivers/video/rockchip/display-sys.c b/drivers/video/rockchip/display-sys.c
index c2229187bc9dcf422aae2a1ab0fb0a49138f3593..a4b0d982ca2885d06698b8ff7db338f0e968e4b0 100755 (executable)
--- a/drivers/video/rockchip/display-sys.c
+++ b/drivers/video/rockchip/display-sys.c
@@ -77,6 +77,10 @@ static int mode_string(char *buf, unsigned int offset,
 {
        char v = 'p';
 
+       if (!buf || !mode) {
+               pr_err("%s parameter error %x %x\n", __func__, buf, mode);
+               return 0;
+       }
        if (mode->xres == 0 && mode->yres == 0)
                return snprintf(&buf[offset], PAGE_SIZE - offset, "auto\n");
 /*