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    Subject[PATCH v2] openvswitch: Fix condition check in do_execute_actions() by using nla_ok()
    Date
    Just using 'rem > 0' might be unsafe, so it's better
    to use the nla_ok() instead.
    Because we can see from the nla_next() that
    '*remaining' might be smaller than 'totlen'. And nla_ok()
    will avoid it happening.
    For example, ovs_dp_process_packet() -> ovs_execute_actions()
    -> do_execute_actions(), and attr comes from OVS_CB(skb)->input_vport,
    which restores the received packet from the user space.

    Fixes: ccb1352e76cff0524e7ccb2074826a092dd13016
    ('net: Add Open vSwitch kernel components.')
    Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
    ---
    net/openvswitch/actions.c | 3 +--
    1 file changed, 1 insertion(+), 2 deletions(-)

    diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
    index 77d924a..c23537f 100644
    --- a/net/openvswitch/actions.c
    +++ b/net/openvswitch/actions.c
    @@ -1238,8 +1238,7 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
    const struct nlattr *a;
    int rem;

    - for (a = attr, rem = len; rem > 0;
    - a = nla_next(a, &rem)) {
    + nla_for_each_attr(a, attr, len, rem) {
    int err = 0;

    switch (nla_type(a)) {
    --
    2.7.4
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