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    Subject[PATCH 5.3 06/95] net: sched: ensure opts_len <= IP_TUNNEL_OPTS_MAX in act_tunnel_key
    Date
    From: Xin Long <lucien.xin@gmail.com>

    [ Upstream commit 4f0e97d070984d487df027f163e52bb72d1713d8 ]

    info->options_len is 'u8' type, and when opts_len with a value >
    IP_TUNNEL_OPTS_MAX, 'info->options_len = opts_len' will cast int
    to u8 and set a wrong value to info->options_len.

    Kernel crashed in my test when doing:

    # opts="0102:80:00800022"
    # for i in {1..99}; do opts="$opts,0102:80:00800022"; done
    # ip link add name geneve0 type geneve dstport 0 external
    # tc qdisc add dev eth0 ingress
    # tc filter add dev eth0 protocol ip parent ffff: \
    flower indev eth0 ip_proto udp action tunnel_key \
    set src_ip 10.0.99.192 dst_ip 10.0.99.193 \
    dst_port 6081 id 11 geneve_opts $opts \
    action mirred egress redirect dev geneve0

    So we should do the similar check as cls_flower does, return error
    when opts_len > IP_TUNNEL_OPTS_MAX in tunnel_key_copy_opts().

    Fixes: 0ed5269f9e41 ("net/sched: add tunnel option support to act_tunnel_key")
    Signed-off-by: Xin Long <lucien.xin@gmail.com>
    Reviewed-by: Simon Horman <simon.horman@netronome.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    net/sched/act_tunnel_key.c | 4 ++++
    1 file changed, 4 insertions(+)

    --- a/net/sched/act_tunnel_key.c
    +++ b/net/sched/act_tunnel_key.c
    @@ -135,6 +135,10 @@ static int tunnel_key_copy_opts(const st
    if (opt_len < 0)
    return opt_len;
    opts_len += opt_len;
    + if (opts_len > IP_TUNNEL_OPTS_MAX) {
    + NL_SET_ERR_MSG(extack, "Tunnel options exceeds max size");
    + return -EINVAL;
    + }
    if (dst) {
    dst_len -= opt_len;
    dst += opt_len;

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