hwrng: core - Changed from using strncat to strlcat

The buf is used to hold the list of hwrng devices registered.
The old code ensures we don't walk off the end of buf as we
fill it, but it's unnecessarily complicated and thus difficult
to maintain. Simplify it by using strlcat.
Signed-off-by: NRickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Reviewed-by: NJason Cooper <jason@lakedaemon.net>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/core.c

@@ -281,7 +281,6 @@ static ssize_t hwrng_attr_available_show(struct device *dev,
 					 char *buf)
 {
 	int err;
-	ssize_t ret = 0;
 	struct hwrng *rng;
 
 	err = mutex_lock_interruptible(&rng_mutex);
@@ -289,16 +288,13 @@ static ssize_t hwrng_attr_available_show(struct device *dev,
 		return -ERESTARTSYS;
 	buf[0] = '\0';
 	list_for_each_entry(rng, &rng_list, list) {
-		strncat(buf, rng->name, PAGE_SIZE - ret - 1);
-		ret += strlen(rng->name);
-		strncat(buf, " ", PAGE_SIZE - ret - 1);
-		ret++;
+		strlcat(buf, rng->name, PAGE_SIZE);
+		strlcat(buf, " ", PAGE_SIZE);
 	}
-	strncat(buf, "\n", PAGE_SIZE - ret - 1);
-	ret++;
+	strlcat(buf, "\n", PAGE_SIZE);
 	mutex_unlock(&rng_mutex);
 
-	return ret;
+	return strlen(buf);
 }
 
 static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,