linux-kernel - [PATCH net v2] net/sched: flower: fix possible OOB write in fl_set_geneve

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Message-Id: <20230531102805.27090-1-hbh25y@gmail.com>
Date:   Wed, 31 May 2023 18:28:04 +0800
From:   Hangyu Hua <hbh25y@...il.com>
To:     jhs@...atatu.com, xiyou.wangcong@...il.com, jiri@...nulli.us,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, simon.horman@...igine.com,
        pieter.jansen-van-vuuren@....com
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hangyu Hua <hbh25y@...il.com>
Subject: [PATCH net v2] net/sched: flower: fix possible OOB write in fl_set_geneve_opt()

If we send two TCA_FLOWER_KEY_ENC_OPTS_GENEVE packets and their total
size is 252 bytes(key->enc_opts.len = 252) then
key->enc_opts.len = opt->length = data_len / 4 = 0 when the third
TCA_FLOWER_KEY_ENC_OPTS_GENEVE packet enters fl_set_geneve_opt. This
bypasses the next bounds check and results in an out-of-bounds.

Fixes: 0a6e77784f49 ("net/sched: allow flower to match tunnel options")
Signed-off-by: Hangyu Hua <hbh25y@...il.com>
---

	v2: add "net" tag to title

 net/sched/cls_flower.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index 9dbc43388e57..815c3e416bc5 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -1153,6 +1153,9 @@ static int fl_set_geneve_opt(const struct nlattr *nla, struct fl_flow_key *key,
 	if (option_len > sizeof(struct geneve_opt))
 		data_len = option_len - sizeof(struct geneve_opt);
 
+	if (key->enc_opts.len > FLOW_DIS_TUN_OPTS_MAX - 4)
+		return -ERANGE;
+
 	opt = (struct geneve_opt *)&key->enc_opts.data[key->enc_opts.len];
 	memset(opt, 0xff, option_len);
 	opt->length = data_len / 4;
-- 
2.34.1