From: Miguel García <miguelgarciaroman8@gmail.com>
Date: Mon, 18 Aug 2025 22:02:03 +0000 (+0200)
Subject: ipv6: ip6_gre: replace strcpy with strscpy for tunnel name
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=09bde6fdcd752b4512e7b554a3259e4f6b77c6d1;p=users%2Fwilly%2Flinux.git

ipv6: ip6_gre: replace strcpy with strscpy for tunnel name

Replace the strcpy() call that copies the device name into
tunnel->parms.name with strscpy(), to avoid potential overflow
and guarantee NULL termination. This uses the two-argument
form of strscpy(), where the destination size is inferred
from the array type.

Destination is tunnel->parms.name (size IFNAMSIZ).

Tested in QEMU (Alpine rootfs):
 - Created IPv6 GRE tunnels over loopback
 - Assigned overlay IPv6 addresses
 - Verified bidirectional ping through the tunnel
 - Changed tunnel parameters at runtime (`ip -6 tunnel change`)

Signed-off-by: Miguel García <miguelgarciaroman8@gmail.com>
Link: https://patch.msgid.link/20250818220203.899338-1-miguelgarciaroman8@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 74d49dd6124d..c82a75510c0e 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -329,9 +329,9 @@ static struct ip6_tnl *ip6gre_tunnel_locate(struct net *net,
 	if (parms->name[0]) {
 		if (!dev_valid_name(parms->name))
 			return NULL;
-		strscpy(name, parms->name, IFNAMSIZ);
+		strscpy(name, parms->name);
 	} else {
-		strcpy(name, "ip6gre%d");
+		strscpy(name, "ip6gre%d");
 	}
 	dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN,
 			   ip6gre_tunnel_setup);
@@ -1469,7 +1469,7 @@ static int ip6gre_tunnel_init_common(struct net_device *dev)
 	tunnel = netdev_priv(dev);
 
 	tunnel->dev = dev;
-	strcpy(tunnel->parms.name, dev->name);
+	strscpy(tunnel->parms.name, dev->name);
 
 	ret = dst_cache_init(&tunnel->dst_cache, GFP_KERNEL);
 	if (ret)
@@ -1529,7 +1529,7 @@ static void ip6gre_fb_tunnel_init(struct net_device *dev)
 
 	tunnel->dev = dev;
 	tunnel->net = dev_net(dev);
-	strcpy(tunnel->parms.name, dev->name);
+	strscpy(tunnel->parms.name, dev->name);
 
 	tunnel->hlen		= sizeof(struct ipv6hdr) + 4;
 }
@@ -1842,7 +1842,7 @@ static int ip6erspan_tap_init(struct net_device *dev)
 	tunnel = netdev_priv(dev);
 
 	tunnel->dev = dev;
-	strcpy(tunnel->parms.name, dev->name);
+	strscpy(tunnel->parms.name, dev->name);
 
 	ret = dst_cache_init(&tunnel->dst_cache, GFP_KERNEL);
 	if (ret)