net: ieee802154: adf7242: Fix some potential buffer overflow in adf7242_stats_show()

strncat() usage in adf7242_debugfs_init() is wrong.
The size given to strncat() is the maximum number of bytes that can be
written, excluding the trailing NULL.

Here, the size that is passed, DNAME_INLINE_LEN, does not take into account
the size of "adf7242-" that is already in the array.

In order to fix it, use snprintf() instead.

Fixes: 7302b9d9 ("ieee802154/adf7242: Driver for ADF7242 MAC IEEE802154")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ieee802154/adf7242.c

@@ -1162,9 +1162,10 @@ static int adf7242_stats_show(struct seq_file *file, void *offset)
 
 static void adf7242_debugfs_init(struct adf7242_local *lp)
 {
-	char debugfs_dir_name[DNAME_INLINE_LEN + 1] = "adf7242-";
+	char debugfs_dir_name[DNAME_INLINE_LEN + 1];
 
-	strncat(debugfs_dir_name, dev_name(&lp->spi->dev), DNAME_INLINE_LEN);
+	snprintf(debugfs_dir_name, sizeof(debugfs_dir_name),
+		 "adf7242-%s", dev_name(&lp->spi->dev));
 
 	lp->debugfs_root = debugfs_create_dir(debugfs_dir_name, NULL);