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authorEric Dumazet <edumazet@google.com>2017-12-11 07:17:39 -0800
committerDavid S. Miller <davem@davemloft.net>2017-12-13 13:13:58 -0500
commitb5476022bbada3764609368f03329ca287528dc8 (patch)
tree93662637d298a843940b42d54ca36326f456db95 /net/ipv4/ip_tunnel.c
parentb9b312a7a451e9c098921856e7cfbc201120e1a7 (diff)
ipv4: igmp: guard against silly MTU values
IPv4 stack reacts to changes to small MTU, by disabling itself under RTNL. But there is a window where threads not using RTNL can see a wrong device mtu. This can lead to surprises, in igmp code where it is assumed the mtu is suitable. Fix this by reading device mtu once and checking IPv4 minimal MTU. This patch adds missing IPV4_MIN_MTU define, to not abuse ETH_MIN_MTU anymore. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/ip_tunnel.c')
-rw-r--r--net/ipv4/ip_tunnel.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index fe6fee728ce4..5ddb1cb52bd4 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -349,8 +349,8 @@ static int ip_tunnel_bind_dev(struct net_device *dev)
dev->needed_headroom = t_hlen + hlen;
mtu -= (dev->hard_header_len + t_hlen);
- if (mtu < 68)
- mtu = 68;
+ if (mtu < IPV4_MIN_MTU)
+ mtu = IPV4_MIN_MTU;
return mtu;
}