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From:   Christophe JAILLET <christophe.jaillet@wanadoo.fr>
To:     keescook@chromium.org,
        Michael Hennerich <michael.hennerich@analog.com>,
        Alexander Aring <alex.aring@gmail.com>,
        Stefan Schmidt <stefan@datenfreihafen.org>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Marcel Holtmann <marcel@holtmann.org>
Cc:     linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org,
        kernel-janitors@vger.kernel.org,
        Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        Stefan Schmidt <stefan@osg.samsung.com>,
        linux-wpan@vger.kernel.org, netdev@vger.kernel.org
Subject: [PATCH net] net: ieee802154: adf7242: Fix some potential buffer overflow in adf7242_stats_show()
Date:   Sat, 21 Oct 2023 20:03:53 +0200
Message-Id: <7ba06db8987298f082f83a425769fe6fa6715fe7.1697911385.git.christophe.jaillet@wanadoo.fr>
MIME-Version: 1.0
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Precedence: bulk

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: 7302b9d90117 ("ieee802154/adf7242: Driver for ADF7242 MAC IEEE802154")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 drivers/net/ieee802154/adf7242.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ieee802154/adf7242.c b/drivers/net/ieee802154/adf7242.c
index a03490ba2e5b..cc7ddc40020f 100644
--- a/drivers/net/ieee802154/adf7242.c
+++ b/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);
 
-- 
2.34.1