4.16-stable review patch. If anyone has any objections, please let me know.
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From: Stefano Brivio sbrivio@redhat.com
[ Upstream commit b4331a681822b420511b3258f1c3db35001fde48 ]
A vti6 interface can carry IPv4 as well, so it makes no sense to enforce a minimum MTU of IPV6_MIN_MTU.
If the user sets an MTU below IPV6_MIN_MTU, IPv6 will be disabled on the interface, courtesy of addrconf_notify().
Reported-by: Xin Long lucien.xin@gmail.com Fixes: b96f9afee4eb ("ipv4/6: use core net MTU range checking") Fixes: c6741fbed6dc ("vti6: Properly adjust vti6 MTU from MTU of lower device") Fixes: 53c81e95df17 ("ip6_vti: adjust vti mtu according to mtu of lower device") Signed-off-by: Stefano Brivio sbrivio@redhat.com Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv6/ip6_vti.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/net/ipv6/ip6_vti.c +++ b/net/ipv6/ip6_vti.c @@ -669,7 +669,7 @@ static void vti6_link_config(struct ip6_ else mtu = ETH_DATA_LEN - LL_MAX_HEADER - sizeof(struct ipv6hdr);
- dev->mtu = max_t(int, mtu, IPV6_MIN_MTU); + dev->mtu = max_t(int, mtu, IPV4_MIN_MTU); }
/** @@ -881,7 +881,7 @@ static void vti6_dev_setup(struct net_de dev->priv_destructor = vti6_dev_free;
dev->type = ARPHRD_TUNNEL6; - dev->min_mtu = IPV6_MIN_MTU; + dev->min_mtu = IPV4_MIN_MTU; dev->max_mtu = IP_MAX_MTU - sizeof(struct ipv6hdr); dev->flags |= IFF_NOARP; dev->addr_len = sizeof(struct in6_addr);