[Patch net] net_sched: properly cancel netlink dump on failure

[Cong Wang]

When nla_put*() fails after nla_nest_start(), we need
to call nla_nest_cancel() to cancel the message, otherwise
we end up calling nla_nest_end() like a success.

Fixes: 0ed5269f9e41 ("net/sched: add tunnel option support to act_tunnel_key")
Cc: Davide Caratti <dcara...@redhat.com>
Cc: Simon Horman <simon.hor...@netronome.com>
Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
---
 net/sched/act_tunnel_key.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/net/sched/act_tunnel_key.c b/net/sched/act_tunnel_key.c
index 28d58bbc953e..681f6f04e7da 100644
--- a/net/sched/act_tunnel_key.c
+++ b/net/sched/act_tunnel_key.c
@@ -412,8 +412,10 @@ static int tunnel_key_geneve_opts_dump(struct sk_buff *skb,
                    nla_put_u8(skb, TCA_TUNNEL_KEY_ENC_OPT_GENEVE_TYPE,
                               opt->type) ||
                    nla_put(skb, TCA_TUNNEL_KEY_ENC_OPT_GENEVE_DATA,
-                           opt->length * 4, opt + 1))
+                           opt->length * 4, opt + 1)) {
+                       nla_nest_cancel(skb, start);
                        return -EMSGSIZE;
+               }
 
                len -= sizeof(struct geneve_opt) + opt->length * 4;
                src += sizeof(struct geneve_opt) + opt->length * 4;
@@ -427,7 +429,7 @@ static int tunnel_key_opts_dump(struct sk_buff *skb,
                                const struct ip_tunnel_info *info)
 {
        struct nlattr *start;
-       int err;
+       int err = -EINVAL;
 
        if (!info->options_len)
                return 0;
@@ -439,9 +441,11 @@ static int tunnel_key_opts_dump(struct sk_buff *skb,
        if (info->key.tun_flags & TUNNEL_GENEVE_OPT) {
                err = tunnel_key_geneve_opts_dump(skb, info);
                if (err)
-                       return err;
+                       goto err_out;
        } else {
-               return -EINVAL;
+err_out:
+               nla_nest_cancel(skb, start);
+               return err;
        }
 
        nla_nest_end(skb, start);
-- 
2.14.4