pinctrl: mediatek: Use scnprintf() for avoiding potential buffer over…

…flow

Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffer limit.  Fix it by replacing with scnprintf().

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20200311090644.20287-1-tiwai@suse.de
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/mediatek/pinctrl-paris.c

@@ -611,7 +611,7 @@ ssize_t mtk_pctrl_show_one_pin(struct mtk_pinctrl *hw,
 	} else if (pullen != MTK_DISABLE && pullen != MTK_ENABLE) {
 		pullen = 0;
 	}
-	len += snprintf(buf + len, bufLen - len,
+	len += scnprintf(buf + len, bufLen - len,
 			"%03d: %1d%1d%1d%1d%02d%1d%1d%1d%1d",
 			gpio,
 			pinmux,
@@ -625,10 +625,10 @@ ssize_t mtk_pctrl_show_one_pin(struct mtk_pinctrl *hw,
 			pullup);
 
 	if (r1 != -1) {
-		len += snprintf(buf + len, bufLen - len, " (%1d %1d)\n",
+		len += scnprintf(buf + len, bufLen - len, " (%1d %1d)\n",
 			r1, r0);
 	} else {
-		len += snprintf(buf + len, bufLen - len, "\n");
+		len += scnprintf(buf + len, bufLen - len, "\n");
 	}
 
 	return len;