diff --git a/drivers/mmc/core/bus.h b/drivers/mmc/core/bus.h
index 00a19710b6b4..3f3f24b2a757 100644
--- a/drivers/mmc/core/bus.h
+++ b/drivers/mmc/core/bus.h
@@ -15,7 +15,7 @@
 static ssize_t mmc_##name##_show (struct device *dev, struct device_attribute *attr, char *buf)	\
 {										\
 	struct mmc_card *card = mmc_dev_to_card(dev);				\
-	return sprintf(buf, fmt, args);						\
+	return snprintf(buf, PAGE_SIZE, fmt, args);			\
 }										\
 static DEVICE_ATTR(name, S_IRUGO, mmc_##name##_show, NULL)