usb: fix stack-buffer-underflow issue

Change-Id: I77b72b01a5182680f10d7a0a4a49e0e400ff63f5
Signed-off-by: Yunmi Ha <yunmi.ha@samsung.com>

diff --git a/src/usb/usb-state.c b/src/usb/usb-state.c
index 300df18..043340c 100755 (executable)
--- a/src/usb/usb-state.c
+++ b/src/usb/usb-state.c
@@ -115,6 +115,7 @@ char *usb_state_get_mode_str(unsigned int mode, char *str, size_t len)
 {
        int i;
        int ret;
+       int flag = 0;
 
        if (mode == USB_FUNCTION_NONE) {
                snprintf(str, len, "%s", "");
@@ -127,12 +128,15 @@ char *usb_state_get_mode_str(unsigned int mode, char *str, size_t len)
                                        return str;
                                str += ret;
                                len -= ret;
+                               flag = 1;
                        }
                }
+               if (flag == 1) {
+                       /* eliminate trailing comma */
+                       *(str - 1) = '\0';
+               }
        }
 
-       /* eliminate trailing comma */
-       *(str - 1) = '\0';
        return str;
 }