diff options
| author | Eric Dumazet <edumazet@google.com> | 2017-12-11 07:17:39 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-01-02 20:31:06 +0100 |
| commit | 57dfc3d10e40053e70691260a791bb453f183cfd (patch) | |
| tree | f70fa995ab4c88f46871bf2cdaab593eeff6ab30 /net/ipv4/ip_tunnel.c | |
| parent | aa7f9011bc01b22658d4c255e2feecf0193e092d (diff) | |
ipv4: igmp: guard against silly MTU values
[ Upstream commit b5476022bbada3764609368f03329ca287528dc8 ]
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/ipv4/ip_tunnel.c')
| -rw-r--r-- | net/ipv4/ip_tunnel.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c index e9805ad664ac..4e90082b23a6 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; } |