From: Eric Dumazet <edumazet@google.com>
Date: Thu, 5 Apr 2018 06:39:31 -0700
Subject: vti6: better validate user provided tunnel names
Git-commit: 537b361fbcbcc3cd6fe2bb47069fd292b9256d16
Patch-mainline: v4.17-rc1
References: networking-stable-18_04_10

Use valid_name() to make sure user does not provide illegal
device name.

Fixes: ed1efb2aefbb ("ipv6: Add support for IPsec virtual tunnel interfaces")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 net/ipv6/ip6_vti.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -212,10 +212,13 @@ static struct ip6_tnl *vti6_tnl_create(s
 	char name[IFNAMSIZ];
 	int err;
 
-	if (p->name[0])
+	if (p->name[0]) {
+		if (!dev_valid_name(p->name))
+			goto failed;
 		strlcpy(name, p->name, IFNAMSIZ);
-	else
+	} else {
 		sprintf(name, "ip6_vti%%d");
+	}
 
 	dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN, vti6_dev_setup);
 	if (!dev)