ip6_append_data is used by other protocols and some of them can't
be partially checksummed.  Only partially checksum UDP protocol.
Fixes: 32dce968dd987a (ipv6: Allow for partial checksums on non-ufo packets)
Reported-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Vladislav Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
        /* If this is the first and only packet and device
         * supports checksum offloading, let's use it.
         */
-       if (!skb &&
+       if (!skb && sk->sk_protocol == IPPROTO_UDP &&
            length + fragheaderlen < mtu &&
            rt->dst.dev->features & NETIF_F_V6_CSUM &&
            !exthdrlen)