netdev - [PATCH v2] net: tun: replace strcpy with strscpy for ifr

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Message-Id: <20250811203329.854847-1-miguelgarciaroman8@gmail.com>
Date: Mon, 11 Aug 2025 22:33:29 +0200
From: Miguel García <miguelgarciaroman8@...il.com>
To: netdev@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	willemdebruijn.kernel@...il.com,
	jasowang@...hat.com,
	andrew+netdev@...n.ch,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	skhan@...uxfoundation.org,
	Miguel García <miguelgarciaroman8@...il.com>
Subject: [PATCH v2] net: tun: replace strcpy with strscpy for ifr_name

Replace the strcpy() calls that copy the device name into ifr->ifr_name
with strscpy() to avoid potential overflows and guarantee NULL termination.

Destination is ifr->ifr_name (size IFNAMSIZ).

Tested in QEMU (BusyBox rootfs):
 - Created TUN devices via TUNSETIFF helper
 - Set addresses and brought links up
 - Verified long interface names are safely truncated (IFNAMSIZ-1)

v2:
- Dropped third argument from strscpy(), inferred from field size.

Signed-off-by: Miguel García <miguelgarciaroman8@...il.com>
---
 drivers/net/tun.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index f8c5e2fd04df..ad33b16224e2 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -2800,13 +2800,13 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 	if (netif_running(tun->dev))
 		netif_tx_wake_all_queues(tun->dev);
 
-	strcpy(ifr->ifr_name, tun->dev->name);
+	strscpy(ifr->ifr_name, tun->dev->name);
 	return 0;
 }
 
 static void tun_get_iff(struct tun_struct *tun, struct ifreq *ifr)
 {
-	strcpy(ifr->ifr_name, tun->dev->name);
+	strscpy(ifr->ifr_name, tun->dev->name);
 
 	ifr->ifr_flags = tun_flags(tun);
 
-- 
2.34.1