From b57f0fe6e38b97dc3c2e3836010b8dc3373b1d58 Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Thu, 15 Mar 2018 17:17:13 +0100 Subject: [PATCH] vti6: Fix dev->max_mtu setting [ Upstream commit f8a554b4aa9686bb2c12f6bae516e58783289a03 ] We shouldn't allow a tunnel to have IP_MAX_MTU as MTU, because another IPv6 header is going on top of our packets. Without this patch, we might end up building packets bigger than IP_MAX_MTU. Fixes: b96f9afee4eb ("ipv4/6: use core net MTU range checking") Signed-off-by: Stefano Brivio Acked-by: Sabrina Dubroca Signed-off-by: Steffen Klassert Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- net/ipv6/ip6_vti.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c index 2493a40bc4b1..0e0ab90a4334 100644 --- a/net/ipv6/ip6_vti.c +++ b/net/ipv6/ip6_vti.c @@ -852,7 +852,7 @@ static void vti6_dev_setup(struct net_device *dev) dev->hard_header_len = LL_MAX_HEADER + sizeof(struct ipv6hdr); dev->mtu = ETH_DATA_LEN; dev->min_mtu = IPV6_MIN_MTU; - dev->max_mtu = IP_MAX_MTU; + dev->max_mtu = IP_MAX_MTU - sizeof(struct ipv6hdr); dev->flags |= IFF_NOARP; dev->addr_len = sizeof(struct in6_addr); netif_keep_dst(dev);