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ip6_tunnel: use the right value for ipv4 min mtu check in ip6_tnl_xmit

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[ Upstream commit 82a40777de ]

According to RFC791, 68 bytes is the minimum size of IPv4 datagram every
device must be able to forward without further fragmentation while 576
bytes is the minimum size of IPv4 datagram every device has to be able
to receive, so in ip6_tnl_xmit(), 68(IPV4_MIN_MTU) should be the right
value for the ipv4 min mtu check in ip6_tnl_xmit.

While at it, change to use max() instead of if statement.

Fixes: c9fefa0819 ("ip6_tunnel: get the min mtu properly in ip6_tnl_xmit")
Reported-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Xin Long
2018-08-05 22:46:07 +08:00
committed by Greg Kroah-Hartman
parent f6b82768f9
commit 87e7e8d405
1 changed files with 2 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
net/ipv6/ip6_tunnel.c
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@@ -1133,12 +1133,8 @@ route_lookup:
max_headroom += 8;
mtu -= 8;
}
if (skb->protocol == htons(ETH_P_IPV6)) {
if (mtu < IPV6_MIN_MTU)
mtu = IPV6_MIN_MTU;
} else if (mtu < 576) {
mtu = 576;
}
mtu = max(mtu, skb->protocol == htons(ETH_P_IPV6) ?
IPV6_MIN_MTU : IPV4_MIN_MTU);
if (skb_dst(skb) && !t->parms.collect_md)
skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);