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

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Date:   Thu,  6 Sep 2018 14:50:16 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     netdev@...r.kernel.org
Cc:     Cong Wang <xiyou.wangcong@...il.com>,
        Davide Caratti <dcaratti@...hat.com>,
        Simon Horman <simon.horman@...ronome.com>
Subject: [Patch net] net_sched: properly cancel netlink dump on failure

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 <dcaratti@...hat.com>
Cc: Simon Horman <simon.horman@...ronome.com>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.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