linux-kernel - [PATCH][next] net/sched: act_pedit: Use flex_array

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Message-ID: <20200730031700.GA23745@embeddedor>
Date:   Wed, 29 Jul 2020 22:17:00 -0500
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>
Subject: [PATCH][next] net/sched: act_pedit: Use flex_array_size() helper in
 memcpy()

Make use of the flex_array_size() helper to calculate the size of a
flexible array member within an enclosing structure.

This helper offers defense-in-depth against potential integer
overflows, while at the same time makes it explicitly clear that
we are dealing with a flexible array member.

Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
---
 net/sched/act_pedit.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/sched/act_pedit.c b/net/sched/act_pedit.c
index 66986db062ed..c158bfed86d5 100644
--- a/net/sched/act_pedit.c
+++ b/net/sched/act_pedit.c
@@ -436,8 +436,7 @@ static int tcf_pedit_dump(struct sk_buff *skb, struct tc_action *a,
 		return -ENOBUFS;
 
 	spin_lock_bh(&p->tcf_lock);
-	memcpy(opt->keys, p->tcfp_keys,
-	       p->tcfp_nkeys * sizeof(struct tc_pedit_key));
+	memcpy(opt->keys, p->tcfp_keys, flex_array_size(opt, keys, p->tcfp_nkeys));
 	opt->index = p->tcf_index;
 	opt->nkeys = p->tcfp_nkeys;
 	opt->flags = p->tcfp_flags;
-- 
2.27.0