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    SubjectRe: [PATCH net] ipv6: Add lwtunnel encap size of all siblings in nexthop calculation
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    ok, I will send v2 version

    在 2023/2/14 11:45 PM, David Ahern 写道:
    > On 2/14/23 2:29 AM, Lu Wei wrote:
    >> In function rt6_nlmsg_size(), the length of nexthop is calculated
    >> by multipling the nexthop length of fib6_info and the number of
    >> siblings. However if the fib6_info has no lwtunnel but the siblings
    >> have lwtunnels, the nexthop length is less than it should be, and
    >> it will trigger a warning in inet6_rt_notify() as follows:
    >>
    >> WARNING: CPU: 0 PID: 6082 at net/ipv6/route.c:6180 inet6_rt_notify+0x120/0x130
    >> ......
    >> Call Trace:
    >> <TASK>
    >> fib6_add_rt2node+0x685/0xa30
    >> fib6_add+0x96/0x1b0
    >> ip6_route_add+0x50/0xd0
    >> inet6_rtm_newroute+0x97/0xa0
    >> rtnetlink_rcv_msg+0x156/0x3d0
    >> netlink_rcv_skb+0x5a/0x110
    >> netlink_unicast+0x246/0x350
    >> netlink_sendmsg+0x250/0x4c0
    >> sock_sendmsg+0x66/0x70
    >> ___sys_sendmsg+0x7c/0xd0
    >> __sys_sendmsg+0x5d/0xb0
    >> do_syscall_64+0x3f/0x90
    >> entry_SYSCALL_64_after_hwframe+0x72/0xdc
    >>
    >> This bug can be reproduced by script:
    >>
    >> ip -6 addr add 2002::2/64 dev ens2
    >> ip -6 route add 100::/64 via 2002::1 dev ens2 metric 100
    >>
    >> for i in 10 20 30 40 50 60 70;
    >> do
    >> ip link add link ens2 name ipv_$i type ipvlan
    >> ip -6 addr add 2002::$i/64 dev ipv_$i
    >> ifconfig ipv_$i up
    >> done
    >>
    >> for i in 10 20 30 40 50 60;
    >> do
    >> ip -6 route append 100::/64 encap ip6 dst 2002::$i via 2002::1
    >> dev ipv_$i metric 100
    >> done
    >>
    >> ip -6 route append 100::/64 via 2002::1 dev ipv_70 metric 100
    > would be good to add that test to
    > tools/testing/selftests/net/fib_tests.sh
    >
    > along with a similar one for IPv4.
    >
    >> This patch fixes it by adding nexthop_len of every siblings using
    >> rt6_nh_nlmsg_size().
    >>
    >> Fixes: beb1afac518d ("net: ipv6: Add support to dump multipath routes via RTA_MULTIPATH attribute")
    >> Signed-off-by: Lu Wei <luwei32@huawei.com>
    >> ---
    >> net/ipv6/route.c | 11 ++++++-----
    >> 1 file changed, 6 insertions(+), 5 deletions(-)
    >>
    > Reviewed-by: David Ahern <dsahern@kernel.org>
    >
    >
    > .

    --
    Best Regards,
    Lu Wei

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