[PATCH net] net: sched: cls_flower: validate nested enc_opts_policy to avoid build warning

[Jakub Kicinski <jakub.kicinski@netronome.com>]

TCA_FLOWER_KEY_ENC_OPTS and TCA_FLOWER_KEY_ENC_OPTS_MASK can only
currently contain further nested attributes, which are parsed by
hand, so the policy is never actually used.  Add the validation
anyway to avoid potential bugs when other attributes are added
and to make the attribute structure slightly more clear.  Validation
will also set extact to point to bad attribute on error.

Fixes: 0a6e77784f49 ("net/sched: allow flower to match tunnel options")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Simon Horman <simon.horman@netronome.com>
---
 net/sched/cls_flower.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index 9aada2d0ef06..c6c327874abc 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -709,11 +709,23 @@ static int fl_set_enc_opt(struct nlattr **tb, struct fl_flow_key *key,
 			  struct netlink_ext_ack *extack)
 {
 	const struct nlattr *nla_enc_key, *nla_opt_key, *nla_opt_msk = NULL;
-	int option_len, key_depth, msk_depth = 0;
+	int err, option_len, key_depth, msk_depth = 0;
+
+	err = nla_validate_nested(tb[TCA_FLOWER_KEY_ENC_OPTS],
+				  TCA_FLOWER_KEY_ENC_OPTS_MAX,
+				  enc_opts_policy, extack);
+	if (err)
+		return err;
 
 	nla_enc_key = nla_data(tb[TCA_FLOWER_KEY_ENC_OPTS]);
 
 	if (tb[TCA_FLOWER_KEY_ENC_OPTS_MASK]) {
+		err = nla_validate_nested(tb[TCA_FLOWER_KEY_ENC_OPTS_MASK],
+					  TCA_FLOWER_KEY_ENC_OPTS_MAX,
+					  enc_opts_policy, extack);
+		if (err)
+			return err;
+
 		nla_opt_msk = nla_data(tb[TCA_FLOWER_KEY_ENC_OPTS_MASK]);
 		msk_depth = nla_len(tb[TCA_FLOWER_KEY_ENC_OPTS_MASK]);
 	}
-- 
2.17.1